Neutral Citation Number: [2011] EWHC 477 (Ch)
Case No: HC06C04408
IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION

Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 7 March 2011

Before :

THE HON MR JUSTICE ARNOLD
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Between :

	(1)	MVF3 APS (FORMERLY VESTERGAARD FRANDSEN A/S)
(2)	VESTERGAARD FRANDSEN SA
(3)	DISEASE CONTROL TEXTILES SA	Claimants	
	- and -		
	(1)	BESTNET EUROPE LIMITED
(2)	3T EUROPE LIMITED
(3)	INTECTION LIMITED
(4)	INTELLIGENT INSECT CONTROL LIMITED
(5)	TORBEN HOLM LARSEN
(6)	TRINE ANGELINE SIG	Defendants	

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Mark Platts-Mills QC, Tom Moody-Stuart and James Whyte (instructed by Field Fisher Waterhouse LLP) for the Claimants
Martin Howe QC and George Hamer (instructed by McGuireWoods London LLP) for the First, Second, Fifth and Sixth Defendants

Hearing dates: 22-24 February 2011
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Approved Redacted Judgment

I direct that pursuant to CPR PD 39A para 6.1 no official shorthand note shall be taken of this Judgment and that copies of this version as handed down may be treated as authentic.

.............................

THE HON MR JUSTICE ARNOLD

MR. JUSTICE ARNOLD : 

Contents
Topic												Paragraphs
Introduction										1-3
Procedural history									4-42
Proceedings at first instance							4-26
Proceedings in the Court of Appeal						27-37
Subsequent proceedings							38-42
The effect of the Court of Appeal’s order dated 24 November 2010	43-60
Should VF have disclosed the Documents before?		    		61
The role of the expert evidence at this hearing					62
Professor Stevens’ evidence								63-68
Should an adverse inference be drawn from
VF’s failure to call factual witnesses?						69-70
The PCT Application									71-90
The Documents										91-138
Z617 trial (October-November 2006)					93
R3 trial (December 2006-January 2007)					94-97
R4 and R7 trials (February-March 2007)					98-113
R12 trial (May 2007)								114-123
R15 trial (June 2007)								124-127
R16 trial (June 2007)								128
R25 trial, Phase 1 (October 2007)						129-132
R25 trial, Phase II (May 2008)						133-135
R25 trial, Phase III (July 2008)						136-138
Question (i)										139-146
Question (ii)										147-148
Question (iii)										149
Conclusion											150
Introduction
1.	On 3 April 2009 I handed down in private a confidential judgment in this matter ([2009] EWHC 657 (Ch), “the main judgment”) holding that the Defendants were liable for breach of confidence through misuse of the Claimants’ (“VF’s”) trade secrets. (Subsequently a redacted version of the main judgment was made available to the public.) In the main judgment I left over for further argument the question of what remedies VF were entitled to. On 26 June 2009 I handed down in private a confidential judgment on that question and a number of related matters ([2009] EHWC 1456 (Ch), “the remedies judgment”). (Again, a redacted version of the remedies judgment was made available to the public later.) After further argument on costs and other matters, I made a final order on 2 July 2009. I refused the Defendants permission to appeal against the main judgment since the Defendants were seeking to challenge my findings of fact, but I granted both parties permission to appeal against my decision as to an injunction in the remedies judgment. 
2.	As explained in more detail below, the First, Second, Fifth and Sixth Defendants applied to the Court of Appeal for permission to appeal and subsequently for permission to adduce further evidence. On 24 November 2010 the Court of Appeal ordered that:
“There be remitted for determination by the Chancery Division before Arnold J the following questions of fact, namely:
(i)	how strongly the migration rate of deltamethrin is affected by the addition of LDPE to the polymer mix;
(ii)	how that effect (if any) compares to the effect of the three additives referred to in paragraphs 121(i)-(iii) of the judgment of Arnold J dated 3 April 2009;
(iii)	whether the outcome of issues (i) and (ii) above renders the Fence results not useful for the formulation of the Defendants’ product.”
3.	This is my judgment on those questions. Before going further, I should point out that a proper understanding of this judgment is only possible if the reader has already read the whole of the main judgment and at least [1]-[11] of the remedies judgment, although I shall cross-reference particularly relevant passages in the earlier judgments.
Procedural history
Proceedings at first instance
4.	The procedural history of the proceedings at first instance is described in some detail in the main judgment at [51]-[79]. For present purposes it is necessary to recapitulate certain points and add others.
5.	The proceedings were commenced by a Claim Form issued on 19 December 2006. On 27 March 2007 the Defendants applied to strike out VF’s claim (see the main judgment at [57]). The Defendants’ application was supported by, inter alia, an expert report from Professor Gary Stevens dated 13 June 2007 (again, see the main judgment at [57]). Paragraphs 1 and 14 of that report recorded that Professor Stevens had been assisted by Dr Henryk Herman. Paragraph 49 recorded that Dr Herman had worked on Innovene polymers and formulation during his employment with BP plc.
6.	Professor Stevens summarised his conclusions as follows:
“3.	This report will show that in my professional opinion the information used to achieve the Netprotect product could all have been obtained from the public domain and from industrial information sources which are not secret. Such information is made available by both polymer and additives manufactures [sic].
4.	I conclude that the two products are significantly different in respect of the polymer blend used, the additives and additive concentrations used, the absence of certain additives in the Claimant’s product which only appear in Netproduct including the [ADDITIVE M] processing additive which enables the polymer melt to be extruded at lower temperatures. I consider the final Netprotect product to be an independent development and one that has distinct process differences to that of the Claimant’s product.
5.	I further conclude that it is possible that the experience and knowledge gained by the Defendants when working for the Claimant may have contributed to the selection of additives in the early exploratory phase of the Netprotect development. However, it is clear that this same starting position could have been obtained from the public literature and that the final product developed is significantly different to both the Claimant’s product and the initial trial materials produced by the Defendant’s [sic] in their own development. I conclude the final product developed by the Defendants is original and of independent design.”
7.	In paragraphs 25-38 Professor Stevens discussed in detail the use of additives in polymers such as polyethylene. During the course of this passage he said this in paragraph 35 (quoted in the main judgment at [604]):
“The benefits of plastics additives are not marginal – they make the difference between success and failure in plastics technology.”
8.	In paragraphs 75 and 76 of his report Professor Stevens stated:
“75.	The interaction between insecticide in the polymer matrix is complex and difficult to predict. A change in the polyethylene matrix will make a big difference to the retention and migration of the insecticide within the polyethylene. The complexity relates to the change in the matrix acidity that the insecticide may introduce, which may affect polymer degradation, and to insecticide induced changes in crystallisation behaviour and morphology development from the melt following extrusion all of which may affect insecticide retention and loss rates. Insecticides may also interfere with the action of polymer additives and additives may also confer protection to the insecticide, such as improving heat stability and reducing the potential for oxidation.
76.	Laboratory and experimental studies have explored relations between host polymer, insecticide, formulation, dosage, and effect. Durability also varies for different polymer hosts. The role of additives and polymer morphology in assisting the dispersion, retention and appropriate release of the insecticide are therefore key factors and it is clear that this is a poorly understood area where more research is needed is a design approach to formulation is to be adopted in the future. In most cases reliable formulations at [sic] arrived at by trial and error following initial guidance from polymer and additive manufacturers with experience in related applications (e.g. agricultural films).”
9.	In both paragraphs 98-99 and paragraphs 111-112 of his report Professor Stevens pointed to differences between the polymer composition of VF’s Fence product (according to the 65.F.0304.5 recipe, as to which see the main judgment at [53], [274], [346] and [608]) and Bestnet’s Netprotect product (as recorded in the document entitled “NPT details.doc”, as to which see the main judgment at [60], [518] and [523]). Thus in paragraph 112 he said:
“The bases [sic] polyethylene compositions of the VF and Netprotect products are very different. The Fence recipe 65.F.0 304.5 gives a polyethylene matrix that is [REDACTED]% HDPE, [REDACTED]% LDPE with the balance in additives. The Netprotect recipe [NPT details.doc] provides a polyethylene matrix that is [REDACTED]% HDPE, [REDACTED]% MDPE, [REDACTED]% LLDPE, [REDACTED]% LDPE, with the balance in additives. These are very different polymer compositions which require different additive combinations.”
10.	The Defendants’ strike-out application was dismissed by Roger Wyand QC sitting as a Deputy High Court Judge on 27 October 2007 (see the main judgment at [65]). 
11.	In late October 2008 the parties exchanged experts’ reports for trial (see the main judgment at [70]). The Defendants served a second report from Professor Stevens dated 21 October 2008. Professor Stevens’ second report repeated most of his first report, including the passages I have quoted in paragraphs 7 and 8 above, with certain additions. Again, he acknowledged the assistance of Dr Herman. 
12.	One of the additions made by Professor Stevens in his second report was of new section 3.04 headed “The Pesticide as an Additive”. This section included the following paragraphs:
“47.	Polyethylene is a simple polymer chain that can pack in a variety of different ways, dependent on the side groups attached to the chain. These prevent the chain ‘packing’ in a regular manner - crystallisation - and leave room for small molecules to impregnate these voids. The polyethylene is a mixture of tightly packed crystallites and amorphous regions, with high-density polyethylene being the most densely packed (density greater than 941 kg/m3 - giving high tensile strength), medium density polyethylene being intermediate (density between 926 and 940 kg/m3 - good stress crack resistance), and low density polyethylene being much less densely packed (density between 910 and 925 kg/m3 - good stress crack resistance). …
48.	The polyethylene blend composition has a profound effect on the retention and storage of the active ingredient in the final product. The additives will tend to be excluded from the crystalline parts of the polyethylene and will segregate to the less ordered and amorphous phase. It is the form and distribution of the crystalline phase in the amorphous phase (the so-called microstructure) that affects the distribution, entrapment and movement of the additives in the polymer matrix. The arising microstructure will be influenced by both the precise nature of the polymer blend and also the nature of the additives and active ingredients present in the hot polymer melt before extrusion and cooling.
49.	The rate of release of additives from the polymeric material will be controlled by the distribution of these crystalline and amorphous phases, and their connectivity. This distribution is particularly sensitive to the temperature and mechanical processing of the polymer but also by the type and concentration of the additive.”
13.	In paragraphs 116-118 Professor Stevens again made the point that the polymer composition of the Defendants’ Netprotect product was very different to that of VF’s Fence product. On this occasion, however, he gave the polymer composition of Netprotect as being [REDACTED]% LDPE, [REDACTED]% LLDPE, [REDACTED]% MDPE and [REDACTED]% HDPE with [REDACTED]% additives. This was said to have been “corrected from that shown, with errors, in ‘NPT details.doc’”. This was the first time that it had been suggested by or on behalf of the Defendants that that document contained errors, and this “correction” was a matter which was never satisfactorily explained by the Defendants (see the main judgment at [526]-[527]).
14.	VF served a report from Gary Howe dated 24 October 2008. In paragraphs 39-63 Mr Howe discussed the structure of polymers, different types of polyethylene and polymer additive interactions. This material is summarised in the main judgment at [117], [119] and [122].
15.	Mr Howe’s report also included the following statements:
“63. 	Within a range of PE materials, migration rates would be expected to increase as the density of the PE material decreases, as the degree of crystallinity reduces and the free volume of the material increases (LDPE can be thought of as having a more ‘open’ structure than HDPE). …
…
364. 	… Furthermore, I would expect the addition of LDPE [to samples in the Defendants’ October 2004 trials] to open the structure of the material slightly and increase the migration rate of the insecticide. …
…
513. 	… Both the reduced deltamethrin content and the removal of LDPE [in the Defendants’ ‘test i marts 2006’ recipes] would be expected to slightly reduce the migration rate, potentially counteracting the [ADDITIVE C] reduction.”
16.	Mr Howe subsequently prepared two further reports which were served by VF, a second report replying to Professor Stevens’ second report and a third replying to Dr Skovmand’s seventh witness statement (see the main judgment at [71], [93]). No reply report from Professor Stevens was served by the Defendants.
17.	One of the assertions made by Dr Skovmand in his seventh witness statement at paragraph 21 was that “extra LDPE in the range [REDACTED] g/kg has a major impact on migration, greater than the effect of any additives”. Mr Howe replied to this in his third report as follows:
“119.	… The results of a linear regression analysis on the Netprotect ‘Screening round 2’ samples are shown in Tables 3, 3b, 3B and 3C of the Defendants’ disclosure document 137 [S5/1456-1458]. The conclusion drawn in this document is that ‘only the impact of [ADDITIVE C] is sure’. The analysis does not show that LDPE has an overriding effect on wash test performance.
120. 	I agree with OS that the migration performance of insecticide-incorporated PE nets will be affected by the base polymer type used. However, the additives do influence the migration of insecticide as described Section 3.3.3 (starting at page 64) of my First Report [K/1/64-70].
121.	At the end of paragraph 152 of his Seventh Witness Statement [D/6/131], OS refers to test conducted in Benin where ‘two identical formulations were tested with and without extra MDPE and LDPE [see pages 65- 68 of OS7]’. However, from the information contained in pages 65-68 of exhibit O7 [E/5/335-337], it is not clear what the formulations of the samples are. Therefore I can make no comment on the performance of these samples.”
18.	Mr Howe gave evidence at trial and was cross-examined, but much of his evidence was not challenged (see the main judgment at [88]-[94]). The unchallenged evidence included the paragraphs in his third report quoted above. The Defendants did not call Professor Stevens to give evidence (see the main judgment at [102]).
19.	Among the witnesses of fact who gave evidence for VF at trial were Sicco Roorda and Phan Quynh Chi (Chi Phan) (see the main judgment at [83], [85]).   Ms Phan’s evidence included the following passage (day 3 page 121):
“Q.  	If you then change the plastic as well, the polymer, because
         	it is for a different purpose, one is for a bed net an[d] one is
         	for a fencing net, you might want to have a different mix of
         	polymers.
A.  	Yes.  If you check, it is not different like if you change
        	from polyethylene to polyester or polypropylene to propylene
         	but even in polyethylene they are different, many time
         	different grades.  So of course when you change the diameter,
          	the process, we would look for the best performance
          	polyethylene, the same polyethylene but different grade, so we
          	call it like more optimizing.
Q.  	So that changes the nature of the net because it may be softer
         	for a bed net but it also changes the whole characteristics of
         	migration within the plastic, does it not?
A.  	It is; changes the migration to some extent.”
20.	The context of this cross-examination was Ms Phan’s evidence in paragraphs 23-29 of her witness statement about VF’s Fence trials. As can be seen from the first question quoted, the cross-examination was directed to the Defendants’ contention that the test data in the Fence database was on samples intended for use as agricultural fencing and thus the information was not useful for the development of a bednet (see the main judgment at [601]-[602]). The proposition advanced by Dr Skovmand in paragraph 21 of his seventh witness statement quoted in paragraph 17 above was not put to Ms Phan.
21.	Neither party adduced at trial any experimental evidence of the kind that is frequently adduced in patent cases, that it to say, evidence of experiments carried out for the purposes of the proceedings directed to one or more issues in those proceedings.
22.	The single most important, and most disputed, factual issue in the case at trial was the source of the Defendants’ Netprotect formulations, and in particular the recipes used in the October 2004 trials. VF contended that these recipes were derived from VF’s Fence database, whereas the Defendants disputed this. I considered this issue in detail in the main judgment at [537]-[621]. For the reasons given there (which drew upon findings elsewhere in the main judgment), I concluded as follows at [620]:
“I find that, when devising the initial recipes for Netprotect, Dr Skovmand started from the Fence formulations which had been bioassayed and found to give good results, namely samples 7-16 and in particular samples 8, 9 and 13. … He expected success with one of these formulations, or a variant of those formulations.”
23.	Among the matters which I considered in reaching this conclusion was the contention advanced in the Defendants’ skeleton argument for trial that the allegation that Dr Skovmand copied from the Fence database rested upon seven improbabilities. Even though none of these points featured strongly in the Defendants’ closing submissions at trial, I considered each of these supposed improbabilities at [600]-[609].
24.	In relation to the third improbability I held as follows:
“604.	(3) It was said that the reason why Netprotect was successful was not due to its additives, but due its polymer composition and manufacturing process. In particular, the Defendants relied on the contention that Netprotect contained LLDPE and MDPE, but the Fence samples did not, enabling a lower extrusion temperature to be employed. As to this, the evidence not only of Mr Howe but also of the Defendants’ expert Professor Stevens was that additives play an important role in polymer processing. Thus in his report made in support of the Defendants’ application to strike out the claim Professor Stevens said:
‘The benefits of plastics additives are not marginal – they make the difference between success and failure in plastics technology.’
Furthermore, it is clear from the evidence in this case that the choice and concentration of the additives makes a difference to the performance of the product, in particular so far as migration of deltamethrin is concerned. 
605.	I accept that polymer composition and manufacturing process are also relevant factors, but as discussed above the Defendants’ production runs of Netprotect have not always included LLDPE or MDPE, or even LDPE. I would also observe that the Netprotect database shows that, contrary to the Defendants’ claim to employ an extrusion temperature of [TEMPERATURE 3], the more recent samples were extruded at [TEMPERATURE 4]. In any event, however, I consider that the relevance of these factors is not to the question of the source of the early Netprotect recipes, but to another issue which I will consider below.”
25.	In relation to the fourth improbability I held at [606]:
“(4) It was said that the migration rate was strongly affected by the polymer composition and so the Fence results were useless in principle. This submission was unsupported by evidence. To the contrary, Mr Howe gave unchallenged evidence that the available data does not enable any such conclusion to be drawn.”
26.	As related in the remedies judgment at [2]-[5], both VF and the Defendant launched applications to re-open findings in the main judgment after it had been handed down, but later withdrew those applications. I nevertheless commented on the points raised by the Defendants. One of the findings which the Defendants sought to re-open was that at [606] in the main judgment. In relation to this I said at [11]:
“The Defendants again contend that I misdirected myself since there was evidence that the migration rate [was] affected [by] the polymer composition. I am perhaps guilty of having expressed myself insufficiently precisely in [606]. It is true that there was evidence that the migration performance of insecticide-incorporating PE nets is affected by the base polymer type used, but the question is whether the addition of LDPE in the quantities used by the Defendants had an important effect. Mr Howe’s unchallenged evidence was that the available data did not establish this. Mr Howe also pointed out that it was unclear what polymer blends the Defendants had used when or how they had been developed. This again is a matter I have dealt with elsewhere in the main judgment.”
Proceedings in the Court of Appeal
27.	As stated above, the First, Second, Fifth and Sixth Defendants (who I will refer to simply as “the Defendants”) applied for permission to appeal. On 20 November 2009 Jacob LJ directed that the Defendants’ application for permission against the findings in the main judgment be adjourned to a two-judge Court on notice to VF. On 9 February 2010 the Court of Appeal (Carnwath and Jacob LJJ) granted the Defendants permission to appeal.
28.	On 11 February 2010 International Patent Application No. WO 2010/015256 (“the PCT Application”) in the name of the Second Claimant was published by the World Intellectual Property Office under the Patent Co-Operation Treaty. The PCT Application was filed on 23 July 2009 claiming priority from a Danish application dated 6 August 2008. 
29.	On 10 May 2010 the Defendants applied to the Court of Appeal for an order that:
“(i) 	on the hearing of the Appeal, the Defendants be entitled to rely upon additional evidence, that evidence being the VF polymer specification (WO 2010/015256 A2); and
(ii)	should any further disclosure be obtained as a result of (iii) below, the Defendants be at liberty to rely upon those documents if relevant;
(iii)	the Claimants be ordered to give further disclosure of any additional documents allied to the specification mentioned above and the research upon which the specification was based or which has taken place after the applications leading to the specification was filed, as more particularly set out in the draft Order attached;
because the specification supports a key element of the Defendants’ case which was rejected by the Trial Judge on the basis of lack of evidence.”
30.	This application came before the Court of Appeal (Jacob LJ and Kitchin J) on 8 October 2010. The Court ordered that the application for permission to adduce further evidence be adjourned to the full Court of Appeal for a decision. In the meantime the Court ordered that:
“the Claimants do disclose to the Defendants Patent Specification No. WO2010/015256 and all documents recording the results of the studies, trials and experiments referred to in the passage from page 11 line 11 to page 12 line 11 of the said specification.”
31.	The Court did not give a reasoned judgment setting out its reasons for making this order. In particular, the Court of Appeal made no finding that the documents which it ordered to be disclosed were relevant to the issues arising on the appeal. Reading the transcript of the proceedings, it appears that the Court of Appeal was unable to decide whether the documents were relevant or not, but considered that they might be and therefore ordered disclosure.
32.	VF duly gave the disclosure ordered in tranches commencing on 22 October 2010. The disclosure exercise involved investigations and searches in Denmark, Switzerland, Germany, India and Vietnam. A total of 108 documents were disclosed. I shall refer to these as “the Documents”.
33.	On 12 November 2010 the Defendants served an expert report from Professor Stevens (which I will refer to as his third report). In this report Professor Stevens set out his interpretation of the PCT Application and of the Documents. Although he brought his expertise to bear upon the interpretation of the Documents, his report did not contain any independent investigations of his own. He recorded that he had been assisted by Dr Herman and Dr Linda Lim.
34.	On 16 November 2010 the Defendants applied to the Court of Appeal for an order that:
“the Defendants have permission to adduce in evidence and rely upon the report of Professor Gary Stevens for the Court of Appeal dated 12 November 2010 because it has been prepared to assist the Court in understanding the relevance to the appeal of technical documents disclosed by the Claimant [sic] pursuant to the Order of the Court of Appeal made on 8 October 2010.”
35.	On 17 November 2010 the Defendants served a notice of intention to rely upon hearsay evidence in respect of a considerable number of the Documents.
36.	The Defendants’ application dated 16 November 2010 came before the Court of Appeal (Jacob LJ and Norris J) on 24 November 2010. The Court made an order paragraph 1 of which remitted to me the questions set out in paragraph 3 above. The order also included the following directions:
“2.	The Defendants have permission to adduce before the Chancery Division for the purposes of said determination the following evidence:
(i)	PCT Application WO 2010/015256.
(ii)	Professor Stevens’ expert report dated 12 November 2010.
(iii)	The four documents numbered 16, 43, 52 and 58 disclosed by the Claimants pursuant to the order of the Court of Appeal dated 8 October 2010.
(iv)	The other documents disclosed by the Claimants pursuant to the order of the Court of Appeal dated 8 October 2010 that are referred to in said report of Professor Stevens.
3.	The Claimants have permission to adduce before the Chancery Division for the purposes of such determination the following evidence:
(i)		An expert report from Mr Gary Howe.
(ii)	One or more witness statements containing any factual evidence on which they wish to rely relating to the statements in the documents set out in paragraph 2(iii) above.
…
7.	The hearing of the appeal be adjourned to be re-listed to take place as soon as reasonably practicable after the said determination by Arnold J …”
37.	Presumably, paragraph 2 of this order overrides paragraph 1 of the order dated 8 October 2010, which adjourned the Defendants’ application to adduce further evidence to the full Court of Appeal, even though the full Court did not sit on 24 November 2010. Again, the Court did not give a reasoned judgment setting out its reasons for making the order dated 24 November 2010. In particular, it made no finding that the materials listed in paragraph 2 of its order satisfied the criteria for the admission of new evidence on appeal (as to which, see the case law discussed in Civil Procedure (2010 edition) at §52.11.2). Reading the transcript of the proceedings, it appears that the Court of Appeal considered that it was arguable that those criteria were satisfied and that remittal was a convenient way of dealing with the issues raised by the new evidence. 
Subsequent proceedings
38.	On 10 December 2010 I made an order by consent listing the trial of the remitted issues for 22 and 23 February 2011 and giving the Defendants permission to adduce reply evidence limited to the issues set out in paragraph 1 of the Court of Appeal’s order dated 24 November 2010. At around the same time the appeal was re-listed for 16 March 2011.
39.	On 13 December 2010 VF served a fourth report of Mr Howe. VF did not serve any witness statements.
40.	On 31 January 2011 the Defendants served a supplementary report from Professor Stevens (which I will refer to as his fourth report). On 15 February 2011 VF served a fifth report of Mr Howe. On 17 February 2011 the Defendants served a second supplementary report from Professor Stevens (his fifth report).
41.	Again, neither side has adduced any experimental evidence of the kind adduced in patent actions.
42.	At the hearing Professor Stevens was called and cross-examined by counsel for VF. In the light of that cross-examination, VF elected not to call Mr Howe.
The effect of the Court of Appeal’s order dated 24 November 2010
43.	The general rule is that this Court has no jurisdiction to re-try an issue which it has already decided once the order is sealed unless the Court of Appeal directs a re-trial: see Spencer Bower and Handley Res Judicata (4th ed) at §5.05.
44.	It appears from the transcript of the proceedings before the Court of Appeal on 24 November 2010 that the Court of Appeal’s intention in making its order was to exercise the power conferred by CPR r. 52.10(2)(b). This provides:
“(2)	The appeal court has power to-
…
(b)	refer any claim or issue for determination by the lower court; 
…”
45.	The exercise of this power has been considered by the Court of Appeal in three recent cases.
46.	In Hicks v Russell Jones & Walker [2007] EWCA Civ 844, [2009] 1 WLR 487 the claimant brought a negligence action against his former solicitors. The trial judge held that the defendant had been negligent in certain respects, but that that had not caused the claimant loss. Accordingly, he awarded the claimant nominal damages, but otherwise dismissed the claim. The claimant was granted permission to appeal. The defendant took the view that, if one of the claimant’s grounds of appeal were substantiated, additional findings of fact would be required which the Court of Appeal might not be able to make. Accordingly, the defendant sought additional findings from the judge on various matters which had been covered in evidence at trial, but on which he had found it unnecessary to make findings. The judge indicated that he was in principle willing to proceed on the basis sought by the application, but only with the approval of the Court of Appeal.
47.	In his judgment Lloyd LJ, with whom Toulson LJ agreed, noted that, in a case where the trial judge had given inadequate reasons for his decision, the Court of Appeal could remit the case to him with an invitation to give additional reasons. (As Maurice Kay LJ has explained in Korashi v Abertawe Bro Morgannwg University Local Health Board [2011] EWCA Civ 187 at [2]-[13], this is a procedure which has become particularly developed in the context of appeals from Employment Tribunals to the Employment Appeal Tribunal.) As Lloyd LJ pointed out, however, in the instant case the judge had given perfectly adequate reasons for his conclusions. What he had arguably failed to do, however, was to make findings on matters that arose contingently if he was held to be wrong on a particular aspect. In this regard Lloyd LJ held at [15]:
“The additional matter to which Mr Livesey has drawn our attention is CPR r 52.10(2)(b), which gives the appeal court power to refer any claim or issue for determination by the lower court. It seems to me that normally that is likely to arise where the appeal court has taken a view that a particular issue is necessary for decision, but that it could be better for it to be decided at first instance. That may be, of course, on allowing an appeal but it seems to me that the power is defined in sufficiently general terms to allow in a case where it appears to be just and convenient for a point to be referred back for determination by the lower court, even if it is only contingently relevant in the context of an appeal that is still pending. That is exactly this case.”
48.	He went on to hold that it was just and convenient to remit the matter to the trial judge for the following reasons:
“17.	It also seems to me that, at any rate, in circumstances in which the judge has the matter fresh in mind, the hearing having been in the course of March, and has indicated that he would be willing to proceed in this way and in which, as I understand it, it is at least contended that he had before him in the course of the trial, so that it would be reflected in the bundles and in the transcript, all the evidence that would be necessary for him to determine any factual issues, that it would be appropriate and conducive to the overriding objective to allow, and indeed direct, that the judge should address the points that contingently arise in relation to the point on which permission to appeal has now been granted.
18.	I should say one or two other things arising consequentially. If the matter does go back to the judge, as I would wish that it should, it will go back on the basis of his indication of willingness to proceed in this way, on the basis of some simple directions with a timetable for written submissions and on the basis that otherwise the rest of the procedure is for him to decide on. He will receive written submissions but he should not receive oral submissions unless he invites them. For my part I do not anticipate that he will need to, or indeed that it will be appropriate for him to, receive additional evidence, but I would not wish to preclude either him or the parties from considering whether additional evidence is necessary on any point.
19.	The only other thing I would say in that respect is that, because the appeal is due for hearing in mid-December, it is highly desirable that his judgment should be available in good time before that date, not least because one or other or indeed possibly both parties may wish to take exception with points that he does decide in the course of the supplemental judgment. As I see it, the status of his decision will be that it is, in effect, a supplement to his original judgment so that if there are points in it with which either party is discontented, and on which an appeal can properly be launched, the relevant party can then seek permission to add relevant points to the appellant's notice or the respondent's notice, as the case may be. Of course it may be necessary that further directions are sought from the Court of Appeal in terms of the future conduct of the appeal.”
49.	This decision shows that the Court of Appeal can exercise the power conferred by r. 52.10(b) even before the substantive appeal has been heard. It is clear from Lloyd LJ’s judgment, however, that the Court was not setting aside or overturning the judge’s order or his original judgment: it was simply directing him to give a supplemental judgment making additional findings of fact on the basis of the evidence already before him in case those findings became material to the pending appeal.  
50.	In Koshy v DEG-Deutsche Investitions- und Entwicklungsgesellschaft mbH [2008] EWCA Civ 27 Mr Koshy brought an action to set aside an interim costs order made by Harman J in earlier proceedings following the dismissal of his application to set aside freezing orders granted by the same judge on the ground that the costs order was obtained by fraudulent misrepresentation or false evidence by DEG. Mr Koshy had previously been granted permission to appeal out of time to the Court of Appeal against Harman J’s costs order on the ground that it had been induced by misrepresentation by DEG. In support of that appeal Mr Koshy had relied on certain findings made by Rimer J (as he then was) in his judgment after the trial of the earlier proceedings. During the course of the appeal hearing, the Court of Appeal pointed out that the normal way of challenging a judgment or order said to have been obtained by fraud was to bring a new action to set it aside. Counsel for Mr Koshy argued that the trial judge’s findings obviated the need for that since they showed that DEG had at least made a material non-disclosure when applying for the freezing orders. DEG then applied to adduce further evidence on question of whether Harman J had been misled. In the light of this, the Court of Appeal gave Mr Koshy the choice between continuing with the appeal solely on the basis of the trial judge’s findings or having the case remitted to the Chancery Division for a trial on the issue of whether there had been material non-disclosure by DEG when applying for the freezing orders. He chose to proceed on the former basis, and so DEG withdrew its application to adduce further evidence. The Court of Appeal dismissed Mr Koshy’s appeal on the ground that the trial judge had not had the issue of non-disclosure before him and his findings had not been directed to that issue. The Court of Appeal also observed that the only way in which Harman J’s order could be satisfactorily reviewed was by an application at first instance in which the relevant facts could be found. Despite this, the subsequent action brought by Mr Koshy was struck out as an abuse of process, and his appeal to the Court of Appeal against that decision was dismissed.
51.	In the course of her judgment on the second appeal, Arden LJ, with whom Ward and Smith LJJ agreed, said this at [45] in relation to the previous hearing before the Court of Appeal:
“ … This court made it clear that they did not consider it appropriate to try any question of fact as to whether the court had been misled: it is trite law that if a person seeks to show that a judgment has been obtained by fraud, he can proceed by way of an appeal or alternatively by way of a fresh action but that he must proceed in the latter way if there are disputed questions of fact. In this instance, this court proposed a third way to obviate the need for a fresh action to resolve disputed issues of fact. That third way was the remission by this court of an issue to the Chancery Division. CPR 52.10(2)(b) provides that this court can remit any claim or issue for determination by the lower court. After Mr Koshy had obtained permission to appeal, DEG had made an application for permission to file fresh evidence thus demonstrating that there were disputed issues of fact. This court therefore proposed the idea of the remission by this court of an issue to the Chancery Division. This court was not bound to do this, especially if no such relief had been claimed in the notice of appeal, but no doubt felt that it would be appropriate to do so since DEG consented to this course at that stage. But what the court was also entitled to do was to prevent the time of the court being wasted by hearing and determining an appeal on a very limited basis only to be faced at the end of the hearing with an application for the remission of an issue to the Chancery Division. Accordingly, as a matter of case management, this court was entitled to offer the option at that stage. If the offer was refused, the appeal would have to be argued on the basis that Mr Koshy would have to convince this court that this court could grant the relief without hearing fresh evidence that DEG sought to produce.”
52.	It can be seen from this that the Court of Appeal considered that, if fresh evidence was admitted by the Court of Appeal which gave rise to a factual issue, the appeal could be disposed of by an order remitting that factual issue to be determined by the lower court pursuant to r. 52.10(2)(b). It seems clear, however, that the Court was contemplating a scenario in which that factual issue had not been determined either by the trial judge in the original proceedings or by the judge who had heard the application to strike out the new action (who, as it happens, was also Rimer J). 
53.	In Noble v Owens [2010] EWCA Civ 224, [2010] 1 WLR 2491 the claimant was awarded substantial damages in personal injury proceedings. The defendant’s insurers subsequently obtained video evidence which they claimed showed that the claimant had given false evidence as to the gravity of his continuing disabilities in respect of which damages had been awarded. The defendant appealed against the award of damages, seeking an order for a retrial, on the grounds that the new evidence demonstrated that the judgment had been obtained by fraud. The claimant accepted that the fresh evidence should be admitted, and adduced exculpatory evidence in response to it. The Court of Appeal held that, where fresh evidence was adduced in the Court of Appeal tending to show that the judge at first instance had been deliberately misled, the Court would not order a retrial unless either the fraud was admitted or the evidence of it was incontrovertible.  In any other case, the issue of fraud had to be determined before the judgment of the court below could be set aside. On the facts, although the defendant's video evidence was sufficiently cogent to be capable of showing that the court below had been deceived, it was far from incontrovertible and was hotly contested. It would therefore be wrong for the award of damages to be set aside unless and until fraud had been proved. In a procedural innovation, the Court of Appeal held that it was not necessary for the defendant to raise its allegation of fraud by way of a new action. Instead, the issue of fraud could be referred to the trial judge pursuant to r. 52.10(2)(b).
54.	Smith LJ, with whom Sedley and Elias LJJ concurred, expressed the Court of Appeal’s disposition of the appeal at [30] in this way:
“I would propose that, for the present, the appeal should be allowed to the extent that the issue of fraud should be referred for trial by a High Court judge. If the judge rejects the allegation of fraud, the original award will stand. If the judge finds that fraud is proved, he should make a reassessment of the damages.”
55.	A number of points should be noted about this. First, the issue of fraud was a new issue arising out of the new evidence which had not previously been determined by any court. Secondly, the Court of Appeal explicitly allowed the appeal to the extent of referring the issue of fraud for trial at first instance. To that extent, therefore, it set aside the judge’s order. Thirdly, the Court of Appeal explicitly stated that, if the allegation of fraud was proved, the trial judge should go on to re-try the issue which he had previously decided.  Thus it was clear that, in that event, the judge’s original award of damages would cease to be res judicata. 
56.	It is not immediately obvious from the three cases discussed above that r. 52.10(2)(b) empowers the Court of Appeal to direct the lower court to reconsider an issue it has already decided prior to the substantive hearing of an appeal. In the present case, the Court of Appeal has not ordered a re-trial, nor has it set aside my order dated 2 July 2009, nor has it disturbed any of the findings upon which that order was based. Prima facie, therefore, the order dated 2 July 2009 is res judicata, and the Defendants are precluded by issue estoppel from challenging my conclusions on all the material issues which led to the making of that order unless and until their appeal is successful. In this regard, it should be noted that the fact the main judgment is presently under appeal does not mean that it is not “final” for the purposes of res judicata: see Spencer Bower and Handley at §5.19. 
57.	Counsel for the Defendants submitted that:
i)	In essence, the Court of Appeal’s order dated 24 November 2010 required this court to reconsider the conclusion contained in the main judgment at [606] as refined in the remedies judgment at [11] (“the Disputed Paragraphs”) in the light of new evidence, namely the PCT Application and the Documents, interpreted with the assistance of the expert evidence. 
ii)	As a matter of necessary implication, the Court of Appeal’s order dated 24 November 2010 should be taken to have set aside the issue estoppel that would otherwise arise out of the main judgment and the remedies judgment to the extent necessary to enable that task to be performed.
58.	Counsel for VF neither took issue with these propositions nor conceded them to be correct.
59.	The effect of the Court of Appeal’s order, and of my determination of the issues remitted to me, seems to me to be a matter for the Court of Appeal at the hearing of the substantive appeal. For the purposes of this judgment, I shall assume, without deciding, that the propositions set out in paragraph 57 above are correct.
60.	I shall also proceed on the assumption that the issues remitted for determination may be significant to the determination of the Defendants’ outstanding appeal even though:
i)	the work reported in the Documents was carried out by VF during the period October 2006 to July 2008, that is to say, approximately 2-4 years after Dr Skovmand devised the initial recipes for Netprotect that were used by the Defendants in their October 2004 trials, and consequently it cannot be suggested that either VF or Dr Skovmand were aware of the work at that time; 
ii)	as explained below, some of the Defendants’ trial formulations and production runs of Netprotect did not include LDPE; 
iii)	[ADDITIVE A], [ADDITIVE B] and [ADDITIVE C] were included in  VF’s and the Defendants’ formulations not only because of their effect on deltamethrin migration, but also for other reasons, in particular to provide protection against UV light (see the main judgment at [121], [163]-[169], [178]-[182]), [186]-[187], [201], [243], [277], [290]-[291], [297], [427], [542], [582] and [617]); and
iv)	my conclusion that Dr Skovmand used the information in the Fence database as his starting point when devising the initial Netprotect formulations was based upon a variety of considerations, including the fact that I concluded that Dr Skovmand was not a witness of truth (see the main judgment at [96]), and not solely upon my rejection of the fourth of the seven improbabilities. 
Should VF have disclosed the Documents before?
61.	Counsel for the Defendants submitted that VF should have disclosed the Documents prior to, or during, the trial. Counsel for VF disputed this. As both counsel agreed, however, this is not an issue remitted to me by the Court of Appeal’s order, and accordingly it is not open to me to determine it. I therefore express no view on it.
The role of the expert evidence at this hearing
62.	Counsel for the Defendants submitted that the role of the expert evidence at this hearing was to assist the court in understanding the Documents and in drawing conclusions from the experimental data they contain. Counsel for VF did not take issue with this submission, and I accept it.
Professor Stevens’ evidence
63.	Professor Stevens obtained a BSc in Physics in 1972 and a PhD in Solid State Polymer Physics in 1975, both from Queen Mary College, University of London. Following a career in industry with the CEGB from 1975 to 1991 and NP plc from 1988 to 1994, he moved to the University of Surrey where he was Research Fellow from 1994 to 2002 and Professor of Polymer Science from 2002 to 2006. Since 2006 he has been managing director of GnoSys UK Ltd and visiting Professor at the University of Surrey. He also has a number of other roles.
64.	I regret to say that Professor Stevens’ evidence was not of the standard to be expected of an expert witness. It became clear in cross-examination that he had relied heavily on Dr Herman to analyse the data contained in the Documents and to assist him with drafting his reports. There is nothing wrong with an expert witness using an assistant, but the cross-examination showed that Professor Stevens had not checked Dr Herman’s work with sufficient care and understanding. Thus Professor Stevens had not spotted some errors in data handling which Dr Herman had made. Nor had Professor Stevens appreciated other flaws in the analyses until they were pointed out to him in cross-examination. As a result, Professor Stevens was forced to resile from significant parts of his reports, and in particular his fourth report.
65.	Of most significance, Professor Stevens resiled from the opinion which he expressed for the first time in his fourth report that analysis of experimental data contained in the Documents showed that “LDPE needs to be present at a critical value to provide the matrix porosity that can then be affected by some of the additives”, that critical value being around 5%.
66.	Two further points should be noted about Professor Stevens’ evidence. The first is that his fourth report, in addition to analysing the experimental data contained in the Documents, included a theoretical discussion of the factors affecting the diffusion rate of additives in polyethylene. The factors he discussed included the extent of the crystalline and amorphous phases of the polyethylene, a matter to which both he and Mr Howe had drawn attention in their reports prior to the trial. But they also included the polarity of the additives, which so far as I can recall was not a factor to which attention was specifically drawn by either expert prior to or at trial, although it would be covered by some of the language they used. In this context Professor Stevens cited a paper by Foldes, “Physical aspects of polymer stablization”, Polymer Degradation and Stability (1995), 57-63. Professor Stevens told me that Dr Herman had drawn this paper to his attention while they were preparing the fourth report and that he (Professor Stevens) had not previously been aware of it. Nevertheless, it is clearly a paper that could have been found and relied upon by the Defendants at trial.
67.	Counsel for the Defendants accepted that it was not open to the Defendants to rely upon the Foldes paper, or upon Professor Stevens’ theoretical discussion more generally, as an independent basis for contending that the Disputed Paragraphs should be reconsidered. He submitted, however, that the evidence was admissible as supporting Professor Stevens’ analysis of the experimental data. I accept that Professor Stevens’ theoretical discussion is admissible, but in my view what matters is the analysis of the experimental data in the Documents. As for the Foldes paper, Professor Stevens did not exhibit it, nor was I was shown it by counsel for the Defendants. In the circumstances I cannot place any weight on it.
68.	The second point is that in his fourth report Professor Stevens reiterated a number of matters which were considered at the trial. Particularly striking is the repetition almost verbatim in paragraphs 103-105 of his fourth report of the comparison between VF’s 65.F.0304.5 Fence recipe and the Defendants’ Netprotect formulation “corrected from [NPT details.doc]” which he had made in paragraphs 116-118 of his second report. That was, of course, evidence which the Defendants had served in advance of, but did not rely upon at, trial. In addition, Professor Stevens’ reiteration of it completely ignores the findings contained in the main judgment on this point (see the main judgment at [523]-[535]).         
Should an adverse inference be drawn from VF’s failure to call factual witnesses? 
69.	Counsel for the Defendants made it clear that the Defendants primarily relied upon statements made by VF personnel in certain of the Documents. He pointed out that the Court of Appeal had given VF permission to adduce factual evidence from relevant witnesses, such as Ms Phan, in relation to the statements made in four of the Documents, but VF had not done so. He submitted that an adverse inference should be drawn from VF’s failure to do this.
70.	I do not accept that submission. What matters for present purposes is what the experimental data reported in the Documents establish as a matter of objective technical fact. What VF’s personnel subjectively thought at the time is only relevant in so far as it sheds light on the objective technical facts. Each of the statements relied upon by the Defendants must be considered in the context of the Document in which it was made, the date upon which it was made and the experimental data to which it refers. But if upon analysis the experimental data do not establish a particular fact, it is immaterial that VF’s personnel may have thought in 2007 or 2008 that they did. Nor should any adverse inference be drawn from VF’s failure to call those persons to explain why they thought what they did. This is particularly so given that the experimental data contained in the Documents has been analysed much more rigorously for the purposes of this hearing than it was by VF’s personnel at the time.   
The PCT Application
71.	The PCT Application is entitled “Insecticidal polymer matrix comprising HDPE and LDPE”. There are six named inventors, including Mr Roorda and Ms Phan.
72.	Under the heading “Background of the Invention”, the specification states at page 1 lines 6-12:
“In connection with insecticide control, it is well known that insecticides can be integrated in polymer material in order to prevent insects to work their way through the material. However, when it comes to the control of release rates of insecticides in a polymer matrix, this is regarded as a difficult issue, because a release that is too rapid exhausts the matrix quickly with regard to insecticidal effect, and a too slow release does not have the desired efficiency or suitable regeneration properties in case the insecticide falls off or is removed, for instance, by washing.”
Thus the problem identified by the specification is to control the release of insecticide incorporated in a polymer matrix so that it is neither too fast nor too slow.
73.	It goes on at page 2 lines 17-33:
“Apart from the difficulty of achieving a suitable migration speed of insecticide in polymer matrices, the combination of an insecticide, for example DM (Deltamethrin), and a synergist, for example PBO (piperonyl butoxide), incorporated in a polymer matrix implies additional challenges. Despite the fact that incorporation of a pyrethroid and PBO has been reported in connection with pet collars, for example in International patent application WO 00/40084 or WO 06/127407, the migration speed for long lasting insecticidal nets (LLIN) or fabrics is still an unresolved problem in practice. This is due to the fact that several parameters have to be fitted together to yield a product that is satisfactory. The parameters have to be found such that, firstly, the insecticidal dose on the surface of the material should be sufficiently high for killing insects, secondly, the release should last for more than a year in the case of LLIN, and should allow regeneration of the net's activity in case of washing of the net, and thirdly, the overall content of the insecticide and synergist should be low in order to keep the cost for LLIN at a minimum, as well as to minimize the potential exposure of an end-user to the active ingredients contained in the net. The latter are important factors, because the largest markets for LLIN are regions with low income, and the primary end-users are infants and young children.”
74.	It should be noted at this point that PBO, which the specification describes as a synergist, is not an additive which featured at the trial of these proceedings at all. For that reason it is not included in the list of additives at [121] of the main judgment. Indeed, so far as I am aware, neither VF nor the Defendants were using it during the periods considered in the main judgment.
75.	The object of the invention is stated at page 3 lines 20-23 to be as follows:
“It is the object of the invention to provide an insecticidal polymer matrix containing HDPE and LDPE with optimised migration capabilities for DM, and, especially, a polymer matrix for producing insecticidal fibres for LLIN and other insecticidal fabrics.”
76.	Under the heading “Description of the Invention”, the specification summarises the invention at page 3 line 25 – page 4 line 2 as follows:
“This purpose is achieved with an insecticidal polymer matrix containing HDPE (high density polyethylene) and LDPE (low density polyethylene). The matrix also contains an insecticide as part of the material of the matrix, that is, the insecticide is incorporated into the material. The insecticide is arranged for migration from inside the material to the surface of the matrix. Further, the ratio of the contents of HDPE and LDPE is between 3 and 30, preferably between 5 and 20, rather higher than 5 and lower than 12, such as between 5 and 11 or 5 and 10, or even between 8 and 10. The insecticide is, preferably, an insecticide different from permethrin, and most preferably, the insecticide is deltamethrin (DM).”
77.	At page 4 lines 20-27 the specification states:
“Preferably, the matrix contains PBO (Piperonyl Butoxide) and DM (Deltamethrin) as part of the material of the matrix.
As experiments have shown, the amount of LDPE in a polymer matrix with HDPE should not be too high, in order to assure an optimal migration rate of the PBO and the DM, whilst concomitantly achieving optimal mechanical properties of the polymer matrix. In this case, both substances migrate to the surface of the material, preferably a mosquito net, and expose the insect to PBO and DM instantaneously.”
78.	At page 5 lines 14-18 the specification states:
“Experimentally, the ratios between PBO and DM were found advantageous in connection with a polymer matrix consisting of HDPE and LDPE, especially for a polymer matrix, where the ratio between HDPE and LDPE is between 5 and 11 or 5 and 10, such as 8 and 10. However, it seems that this is valid as well for polymer matrices, where other polymers are added to HDPE and LDPE.”
79.	At page 5 line 31 to page 11 the specification states:
“The surface content of PBO and DM on the surface of a polymer matrix depends on the migration rate of PBO and DM in the polymer as well as on the thickness of the polymer substrate (i.e. the distance to the surface). The migration rate is influenced by, amongst other factors, the proportion of amorphous phase in the polymer (i.e. the percentage of crystallinity), the diffusion coefficient, which, in turn, is affected by the temperature and the degree of affinity between the additives and the polymer. Therefore, the surface content of DM and PBO at any moment in time is determined by a combination of various thermodynamic effects but also by the shape of the polymeric substrate being in the form of a yarn, a foil, or a bulk product. The above ratios were verified as being useful for an insecticidal matrix in the form of a fully drawn monofilament yarn with a diameter of between 0.05 mm and 0.3 mm, preferably between 0.1 mm and 0.15 mm. Especially, the HDPE and LDPE ratio of between 5 and 10, or rather between 8 and 10, was suitable for such filaments. However, the above figures are also useful for multifilaments having a linear density in the same range.”
80.	At page 8 lines 12-15 the specification states:
“In addition, special migration promotors [sic] or inhibitors may be used to adjust the migration speed. For example, some promotors or inhibitors may work more or less on DM than on PBO, by which the migration speed of these two components can be adjusted relatively.”
There is nothing in the specification to indicate what “migration promotors or inhibitors” the inventors have in mind.
81.	At page 8 lines 21-29 the specification sets out a long list of “other ingredients” which may be included in the polymer matrix, including “UV protectors”. There is nothing in the specification to exclude the possibility that some of these “other ingredients” may also function as “migration promotors or inhibitors”.
82.	Under the heading “Detailed description of the invention” the specification describes the invention by reference to five figures. This section begins with the following statement at page 10 lines 5-11:
“The path leading to the invention did comprise a number of intermediate steps, in as much as the solution, despite its simplicity is not straightforward.
In the teaching in the field of insecticidal nets, it has hitherto been assumed that PBO has to be transferred to the mosquito well in advance to the exposure to DM, because the PBO was believed to need a certain time in the mosquito before it temporarily breaks down the resistance mechanism.”
83.	The specification goes on at page 10 line 26 – page 11 line 9:
“One of the corner stones of the invention is the fact that experiments revealed that the bioefficacy of PBO and DM treatment is highest when mosquitoes were exposed to PBO and DM simultaneously. As described above, this is against the teaching in the field of insecticidal nets. A proof for this is illustrated in FIG. 1, showing that for different dosages, there was a remarkable increase in efficacy when DM and PBO were provided to the mosquito at the same time. 
Having recognised this, there was a new motivation for providing a polymer matrix containing PBO and DM, where both can be found on the surface of the matrix and migrate at a similar rate so as to replenish the surface after depletion (by washing, for instance) in order to expose insects to DM and PBO at the same time. As long as there is a steady release of these two substances, the efficacy against mosquitoes is optimal. Of course, this is compounded by the added constraint for LLINs that the said polymer matrix, once knitted into a netting material, should have suitable migration properties so that PBO and DM be regenerated at the surface of the yarn/fabric following washing.”
84.	The specification then continues with the passage at page 11 line 11 to page 12 line 11 referred to in the Court of Appeal’s order dated 8 October 2010:
“The question then arises, which material should be chosen for the matrix. Studies revealed that polyester has a very slow migration rate, which was not sufficient to release enough DM and PBO through migration of polyester yarn of 100 Denier, even when used a multifilament with 35 filaments. HDPE had a release rate which was higher than for polyester, but not high enough for sufficient insecticidal efficacy or regeneration at a rate suitable for mosquito netting materials, despite good mechanical properties making it suitable for knitting into netting material. On the other hand, LDPE has a migration rate, which is far too high for a LLIN, and yarns made of pure LDPE have low mechanical properties that make them unsuitable for knitting into netting material. Thus, according to the invention, a mixture of LDPE and HDPE was envisaged, and it was found empirically, that for sufficient but also long lasting release of DM and PBO, a mixture of HDPE and LDPE was optimum, where the weight ratio between HDPE and LDPE was between 30 and 3 and rather between 20 and 5. The ratio depends on the thickness of the matrix. For monofilament yarns with a thickness of 0.06 mm, the HDPE/LDPE weight ratio was best between 15 and 25 and for yarns with a thickness of 0.25 mm, the ratio was best between 4 and 7. For yarn thickness in between these two numbers, the ratio may be interpolated. These parameters seem to give the said monofilament yarns adequate crystallinity at a given draw ratio and therefore an appropriate migration rate at the typical temperature these products are used.
In the experiments, no other polymers were introduced into the matrix. The above ratios corresponded in these experiments to a LDPE weight content of between 3.5% and 35% in the HDPE/LDPE matrix, whereas, however, the preferred content of LDPE in terms of weight was between 5% and 17%, better between 8% and 12%.
A successful monofilament yarn with a diameter of 0.10 mm to 0.15 mm, for example around 0.12 mm, the content of HDPE and LDPE in terms of weight was at a ratio between 8 and 10, rather around 9, corresponding to an LDPE content of around 10%, when no other polymers were introduced.
However, as it turned out, not only the ratio between the content of HDPE and LDPE could be used to optimise the yarn with respect to long lasting high efficiency. Also the content of the PBO content relative to the DM content proves to be crucial.”
85.	Although the specification says in this passage that experiments were conducted which apparently led to the conclusion that an LDPE content of around 10% was particularly preferred, no experimental data is reported to substantiate this.  
86.	At page 12 lines 21-27 the specification states:
“Examples of successful yarns had diameters of between 0.10 mm and 0.15 mm, for example around 0.12 mm, containing 4g DM per kg polymer and 25g PBO per kg polymer. For example, the content of HDPE and LDPE in terms of weight at a ratio is between 8 and 10, for example around 9. Due to necessary initial migration before a sufficient content is reached at the surface of the matrix, the yarn, advantageously, can be stored for a certain time to reach sufficient efficacy, for example a week to reach 80% efficacy.”
87.	At page 13 lines 2-11 the specification states:
“The monofilament polyethylene yarns may successfully be used for bed nets, where the entire net is provided with such material. However, in case that the side walls of the nets are preferred to be produced in polyester multifilament due to the relatively higher softness and cotton like feeling, the extruded HDPE/LDPE monofilament yarn may be used for the top part of the net. The efficacy will in most cases still be high, because mosquitoes typically attack their potential victims from above and tend to land on the roof of bed nets, especially rectangular bed nets.
As a further addition, migration promoters may be included in the molten matrix prior to extrusion of the insecticidal polyethylene blend.”
Again, there is nothing in the specification to indicate what “migration promoters” the inventors had in mind.
88.	Claim 1 is as follows:
“An insecticidal polymer matrix made of a material containing high density polyethylene (HDPE) and low density polyethylene (LDPE), and deltamethrin (DM), wherein the DM is part of the material and arranged for migration from inside the material to the surface of the matrix, wherein the ratio of the content of HDPE to LDPE is between 5 and 20 in terms of weight.”
89.	Claim 2 narrows the HDPE to LDPE ratio to between 5 and 11 and claim 3 to between 8 and 10. Claim 4 requires the addition of PBO.
90.	In summary, the invention disclosed and claimed in the PCT Application is that the migration of deltamethrin in insecticidal polyethylene fibres and fabrics can be optimised by using a mixture of HDPE and LDPE. A ratio of 9:1 (i.e. 10% LDPE) is particularly preferred, but no experimental data is disclosed to support the choice of 10% LDPE. The specification points out that migration is also affected by other factors, including (i) the presence of PBO (and the ratio PBO to deltamethrin), (ii) the presence of “migration promotors and inhibitors” and (iii) the thickness of the fibre. 
The Documents
91.	The Documents relate to a series of nine trials from late 2006 until August 2008. Ms Phan and Mr Roorda were among the VF personnel involved in these trials. The trials formed part of VF’s project number 101 to develop its PermaNet 3.0 product. This was intended to have enhanced vector control properties (against resistant mosquito strains) as a result of introducing PBO (which is referred to throughout the Documents by its code name of VF30) as a synergist with deltamethrin. If possible, PermaNet 3.0 was also to have improved longevity and stability of the net, and washability up to 30 washes. The result of this research was the formulation used for the polyethylene roof of PermaNet 3.0 (see the main judgment at [303]). The purpose of the trials was not to compare the relative effects of LDPE and the additives in issue on the migration of deltamethrin.
92.	In these trials VF used a number of analysis techniques to assess the performance of yarn and fabric samples:
i)	Retention index. This is a measure of the loss of active ingredient following an exposure condition (typically a wash cycle). It is commonly expressed as percentage after n washes (where n is often 1), such that retention index = (active ingredient after n washes/active ingredient after zero washes) x 100.
ii)	Release index. This is a measure of the change in surface concentration of an active ingredient. In this test the surface concentration is first determined (surface extractable 1 or SE1), then the surface is cleaned and the sample allowed to regenerate and the surface concentration determined again (SE2) and then that process is repeated (SE3). The release index is the ratio SE2/SE3.
iii)	Bioassay tests. These test the effectiveness of a formulation in terms of its main function of killing mosquitoes as a function of storage time and/or temperature. The insecticidal effect depends on the surface concentration of deltamethrin. Good bio-efficacy requires a moderate rate of migration of deltamethrin to the surface of the yarn or fabric: too high a migration rate leads to rapid depletion of deltamethrin, while too low a migration rate results in poor surface regeneration of deltamethrin after it has been lost due to evaporation and/or washing.
iv)	Storage stability tests. VF was interested in two aspects of storage stability at elevated temperatures. The first concerned loss of active ingredients due to evaporation from the surface. The second concerned isomerisation of deltamethrin to the inactive R-isomer (see the main judgment at [206]). The latter aspect is not relevant to the issues presently before me.    
 Z617 trial (October-November 2006)
93.	This trial involved only polyester. The general conclusion drawn by VF from this trial was that there was minimal migration of deltamethrin or PBO in polyester. Since the trial did not involve LDPE, or any polyethylene, it is common ground that it is not relevant to the issues before me even though it was caught by the wording of the order dated 8 October 2010.
R3 trial (December 2006-January 2007)
94.	As an alternative to using polyester, deltamethrin and PBO were incorporated into polyethylene. The formulations tested all included [ADDITIVE A] and [ADDITIVE B]. Part of the objective was to test a new extrusion method. Samples were made at Aachen University and tested by Ms Phan. Although pure LDPE was used as the matrix (whether by accident or by design is unclear), the significance of this was not appreciated until later.
95.	Document 32 is a report on the project dated 20 March 2007. On page 10 the following conclusions are drawn from this trial:
“PBO was successfully incorporated by the new extrusion method into the PE yarn. We were able to get a product after production with 100% FM towards Culex, EVEN with DM level of 1/10 of the normal used concentration.
This means we have a product that works 100% against Culex, with a very low DM level under the condition that is not washed.
After 3 washes the mortality against Culex drops significant and after 5 W mortality drops to 32% even against susceptible mosquitoes. I.e. the migration of PBO and DM is too fast.
Main issue is to slow down migration rate. This can be done by lowering the migration enhancer and introduce, if needed, a migration inhibitor. Two chemistries are identified to do this and a new test matrix has been agreed upon. Deadlines put very tight.”
96.	The next page of this document sets out the planned test matrix for the next trial (as to which, see below) together with an explanation of the reasoning for the test matrix which begins:
“The migration rate of DM and PBO in PE may be different. We assume PBO migrates faster than DM.
[ADDITIVE A]: Acts as a migration enhancer
[ADDITIVE C]: Act as a migration inhibitor”.
97.	These statements about [ADDITIVE A] and [ADDITIVE C] are entirely consistent with my findings in the main judgment at [224], [243], [251]-[252], [277]-[278], [297], [352], [407], [514] and [551].
R4 and R7 trials (February-March 2007)
98.	The planned test matrix comprised 15 samples S1-S15 based on a pair-wise comparison of formulation changes. S1, S2 and S3 were made in India in February 2007 (referred to as the R4 trial) and the remainder in March 2007 (R7). All of the samples included PBO, but not all included deltamethrin. All included [ADDITIVE B], some included [ADDITIVE A], some included [ADDITIVE C] and some included both. All of the samples were made from pure HDPE, but it does not appear to have been appreciated at the time that this matrix was different to that used for the samples in the R3 trial.
99.	Document 9 is a spreadsheet which contains retention index data following a single wash for the R4 and R7 samples. The data includes figures up to 115%. Since the maximum possible retention is 100%, this indicates errors in the analysis. None of the samples shows a significant difference in deltamethrin retention compared to the other samples, however.  The data for PBO retention are similar. 
100.	In April 2007, comparison of results of tests done on samples from the R3 trial and the R4/R7 trials by VF revealed an unexpected difference between them, when some of the formulations should have been similar. At this point, VF’s personnel appreciated that the difference was that R3 was based on 100% LDPE, whereas R4/R7 were based on 100% HDPE.
101.	Document 16 is a report on the PermaNet 3.0 project that bears an “initiated date” of 12 February 2007, but from its contents appears to date from early April 2007. This document discusses the results from the R4/R7 trials as well as other experimental data. Page 2 of this document includes a graph part of which I reproduce below:
[REDACTED]
102.	The figure of [REDACTED]% for HDPE appears to come from the data in Document 9 discussed in paragraph 99 above. This is the average of the deltamethrin retention values for the samples which contained deltamethrin. Those values range from [REDACTED]% to [REDACTED]%. The standard deviation is [REDACTED]%. The source of the figure of [REDACTED]% for LDPE is unclear, but it appears to be Document 86. This contains data for six samples from the R3 trial with an average retention after one wash of [REDACTED]%. The values range from [REDACTED]% to [REDACTED]%. The standard deviation is [REDACTED]%. The source of the figure of [REDACTED]% for LDPE thin film is unknown, but this figure does not appear to be important for present purposes. As noted above, the HDPE and LDPE samples contained other additives in addition to deltamethrin. 
103.	If one takes the figures of [REDACTED]% deltamethrin retention for 100% HDPE and [REDACTED]% retention for 100% LDPE, and one assumes a linear relationship between LDPE concentration and retention, then a polymer matrix containing 10% LDPE (and the other additives present in these samples) would be expected to have a retention index after one wash of [REDACTED]%. It appears from other Documents discussed below that this was the origin for the HPDE:LDPE ratio of 9:1 which ultimately found its way into the PCT Application. It may be noted, however, that a retention index after one wash of [REDACTED]% in itself tells one nothing about the relative bio-efficacy in terms of killing mosquitoes of a bednet made from such a composition after 20 or 30 washes compared to a bednet made from 100% HDPE.  Still less does it tell one anything about the relative effect on deltamethrin migration of LDPE on the one hand and [ADDITIVE A]/[ADDITIVE B]/ [ADDITIVE C] on the other hand.
104.	On the same page of Document 16 is a comment which appears to relate partly to the graph reproduced above and partly to a graph on page 3 which compares the wash test performance of Netprotect with “PermaNet” and “VF bednet”:
“A too slow migration HDPE drops in bio-efficacy shortly, even still containing more than [REDACTED]% of DM, too fast migration PES coating empties the storehouse very soon at 20W, with about [REDACTED]% DM left. A moderate migration in PE incorporated (Netprotect) is bio-effective upto 35W with [REDACTED]% of DM in storehouse.”
105.	Pages 3 and 4 of this document include the following passages:
“B. LDPE-incorporated
- Migration in LDPE is too fast, consequently, LDPE composition in mixture with HDPE is expected to be the KEY factor in driving migration.
C. PES-incorporated
PES incorporated is also a deadlock of DM and PBO in terms of migration. By any mean-time storage or heat up, we could not get PES incorporated sample to be bio-active. …
D. HDPE incorporated
14 different formulations were made by Gopi/VKA in Mar. 07. These formulation is monofilament, d=[REDACTED] mm, prepared in different colors in groups.
Data on these different 14 different formulations renders the following observations:
1.	Slow migration of both DM and PBO in 100% HDPE netting. This fact is going to be fixed by controlling LDPE percentage.
…
5.	UV stabilisers, [ADDITIVE A] and [ADDITIVE C] show positive role in UV protection of DM, while no clear interaction/protection with VF30. [ADDITIVE B] presents in all samples, therefore the role of [ADDITIVE B] remains are unknown. The fact that samples were in different colors makes any conclusion on UV protections quite shaky.
6.	UV stabilisers, [ADDITIVE A] in theory is migration accelerator under [this sentence appears to be unfinished]”.
106.	The Defendants particularly rely on the statement at B, but having regard not only to the wording used, but also the date on which the statement was used and the materials on which it was based, it is clear that this was a prediction. The same goes for D1. Furthermore, at this stage VF had data on samples containing 100% HDPE and 100% LDPE, but not on mixtures of HDPE and LDPE.
107.	Document 40 is a chain of emails dated 19 and 20 April 2007 which appear to come between the R4/R7 trials and the next trial. In the first email in this chain Ms Phan wrote on 19 April 2007:
“Outcome of recent study on PE PermaNet 3.0, especially from co-incident LDPE sample made at Aachen: by controlling LDPE/HDPE ratio we can control/speed up the migration of DM and VF30 in PermaNet 3.0.
Please come up with a matrix for PermaNet 3.0 based on the direction of LDPE/HDPE mixture.”
This is evidently a deduction from the existing data combined with a proposal to test that deduction.
108.	On 20 April 2007 another VF employee called Thanh Huyen Hoang replied setting out a proposed test matrix in which all the samples were to contain [REDACTED] mg/g [ADDITIVE A], [REDACTED] mg/g [ADDITIVE B] and [REDACTED] mg/g [ADDITIVE C] with varying amounts of deltamethrin, PBO and LDPE. The LDPE contents proposed were [REDACTED]%, [REDACTED]% and [REDACTED]%, described as “low/medium/high LDPE content”. Later the same day Gopi Nath suggested going up to [REDACTED]% LDPE.
109.	Shortly afterwards Ms Phan replied to both Mr Nath and Ms Thanh saying:
“15 recipes S1-S15 was set up based on the picture of R3 – where VF30 was assumed to play bleeding effect in PE. We learn after receiving samples from you (S1-S3) that smt wrong with this hypothesis and only by then we knew that R3 is LDPE.
Not VF30 or any other additatives [sic], but LDPE plays key role in migration. It turns the trial to new direction.
S1-S15, based on pure HDPE, we are trying to grasp as much as possible information out of this. Most focusing on
(1)	additatives’ role in driving migration
(2)	UV protection
Pls. do not worry, your work on S1-S15 is not a waste at all. Testing is still running. But most likely none of them is qualified for PermaNet 3.0 due to generally slow migration. We do not know yet at the moment.
If you face time and stock issue, pls. consider go ahead first with PE5 to PE9. This group tackles the right percentage of LDPE I the mixture. And if we can optimise the LDPE percentage, we can play better with two other groups, PE1-PE4 and, PE10-PE13.
Keyword for this phase is: LDPE percentage:-))).
For [REDACTED]% LDPE, if we can stretch to that far, it is good to have one more point in the curve. 100% LDPE gives RI = [REDACTED]% , 100% HDPE RI = [REDACTED]%.”
110.	The Defendants particularly rely upon the third sentence quoted, suggesting that this represents a recognition on the part of Ms Phan that LDPE was the key factor in controlling migration. I disagree. Read in context, it is clear that Ms Phan had deduced that added LDPE would play a key role and she was proposing to test that deduction. It is clear from the last two sentences I have quoted that the percentages of LDPE she was proposing to test were based on interpolation from the two existing data points for 100% HDPE and 100% LDPE. This is clearer still from a table which follows, in which she interpolates retention values for [REDACTED]%, [REDACTED]% and [REDACTED]% LDPE. There is no warrant for thinking that she had concluded that the other additives had no role in migration. On the contrary, she says that this is being tested as well, although she gives no details of this.
111.	Later the same day Ms Thanh replied proposing a revised matrix which included [REDACTED]% LDPE as well as the same quantities of [ADDITIVE A], [ADDITIVE B] and [ADDITIVE C] as previously proposed. Michael Pedersen, then VF’s Chief Development Officer, then replied saying that he would like to include a trial with PBO alone “and then change the amount of the migration enhancer [ADDITIVE A] in those trials”.  Mr Thanh agreed with this suggestion.
112.	Document 43 is a single slide from a presentation entitled “101 PermaNet 3.0 PBO and DM Technical Review May 2007”. This states:
“PE incorporation – LDPE
Migration in LDPE is too fast
1. High RI under washing
2. Higher LDPE, faster loss to air
LDPE percentage is considered as key driving factor in controlling migration in PE bednet.”
113.	The Defendants particularly rely on the last sentence of this, but the statement is essentially the same as that made by Mr Phan in her email of 19 April 2007. As such, it is obviously based on the same considerations, and gets the Defendants no further forward.   
R12 trial (May 2007)
114.	This was the first trial designed to look at the effect of adding LDPE to HDPE. Despite the discussions on 19-20 April 2007, in the event only five samples (PE1, PE3, PE5, PE7 and PE8) were made, with LDPE levels of [REDACTED]% or [REDACTED]%. The samples either contained [REDACTED] g/kg deltamethrin, or PBO at a concentration of [REDACTED] or [REDACTED] g/kg. [ADDITIVE A] was included in all samples at [REDACTED] g/kg and [ADDITIVE C] at [REDACTED] g/kg. One sample contained [ADDITIVE B] at [REDACTED] g/kg. Document 46 records that this was because of a shortage of [ADDITIVE B]. The same document records production problems with some of the samples, in particular PE3, which appears to explain the absence of test data for this sample.
115.	Document 50 is a spreadsheet which contains analysis data for these samples. There was a good deal of evidence about the interpretation of these data at the hearing. I will set out my findings in the light of this evidence below.
116.	Document 58 contains two emails from Ms Phan discussing these results dated 18 June 2007 and 9 July 2007. The first states:
“A. PE1 with [REDACTED]% LDPE is quite comparable with Netprotect in terms of chemical assay.
(1) RI/DM of PE1 = [REDACTED]%.
(2) Surface content development
PE 1 behaves quite poor in bioassay with aedes, with far from saturated surface at the beginning. This fact requires verification.
B. PE5 and PE7, the only difference is [REDACTED]% and [REDACTED]% LDPE respectively. Higher LDPE, faster surface development. 
(1)	Lower RI of both VF30 and [ADDITIVE A] observed in PE7 and higher surface content development along SE1, SE2, SE3 in chemical assay
(2)	PE7 has higher bio-efficacy at 0W, thanks to [REDACTED]% LDPE. After 1W, faster migration in PE 7 does not compensate for the higher loss during washing, therefore bio-efficacy at 1W is poorer compared to PE5
This point, as Huyen commented in another separate e-mail, [REDACTED]% LDPE might be an extreme for migration.
Let see the balance between migration-loss to wash slide versus number of wash.
C. Compare PE5, PE7 with a group of R7 sample with LDPE = 0%, higher LDPE, higher surface content development relatively.
A,B,C: confirm LDPE drives migration significantly and dominantly.
…
E. Bio-efficacy with culex at 0W and 1W was made with abundant DM source provided by PN 2.0. Data would be compromised if tested with limited DM source as seen in PE1 
>>>Even with high VF30 ([REDACTED] g/kg) and 10% LDPE, bio-efficacy against culex is still an issue to pass 80% FM. Defining a proper goal/text for bio-efficacy against culex is an important task. So far, we can reach 100% FM on Culex only on LDPE 100% sample and few coating samples.
…”
117.	The Defendants particularly rely upon the first emboldened sentence. Even leaving aside for now the question of what the data actually establish, however, this sentence has to be read in context. When this is done, it can be seen that Ms Phan is concluding that the data support the deduction made previously that the addition of LDPE to HDPE has a significant effect on migration of deltamethrin and PBO. This conclusion is based on her observation that the samples with [REDACTED]% LDPE have a higher migration rate/surface concentration development rate than those with [REDACTED]% LDPE, which in turn have a higher rate than the R7 samples with 0% LDPE.
118.	Counsel for the Defendants submitted that the word “dominantly” meant by comparison with [ADDITIVE A]/[ADDITIVE C]/[ADDITIVE B]. I do not accept this submission. In my view it is tolerably clear that it means by comparison with pure HDPE. Ms Phan was not considering the relative effects of LDPE and [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C] on deltamethrin migration.
119.	It is also worth noting that what concerned Ms Phan most was the bio-efficacy of the samples, and that she observed that PE1, which had [REDACTED]% LDPE but no PBO, behaved poorly in the bioassay. Thus simply increasing the migration rate of deltamethrin by adding LDPE did not necessary produce a product with satisfactory bio-efficacy.
120.	Ms Phan’s second email is an update containing further data and discussion. First, she reported the results of a chemical assay using [ADDITIVE A] as an indicator for migration (i.e. using [ADDITIVE A] as a marker for the effect of other ingredients rather than considering its own effect). Her conclusion from  this was as follows:
“1. Higher VF 30 and/or higher LDPE, faster migration seen by chemical assay
…
PE7 against PE5: [REDACTED]% LDPE is faster migration than [REDACTED]% LDPE
PE8 against PE5: Higher VF30, faster migration”.
121.	This email does not suggest that LDPE is dominant. On the contrary, it suggests that both LDPE and PBO affect migration (in circumstances where [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C] are essentially constant).
122.	Secondly, she reported the results of testing bio-efficacy against a number of washes for PE5 ([REDACTED]% LDPE), PE7 ([REDACTED]% LDPE) and PE8 ([REDACTED]% LDPE). Her conclusion from this was as follows:
“Too few data to make a conclusion, especially with famously high method uncertainty as bioassay. Statistically, no difference in bio-efficacy between three formulations.”
123.	Thus increasing the LDPE level from [REDACTED]% to [REDACTED]% was not found to yield a statistically significant difference in bio-efficacy (even disregarding the other differences between these samples). 
R15 trial (June 2007)
124.	The plan in this trial was to test a matrix of 15 samples made in India. The formulations were predominantly PBO-based, with only four containing deltamethrin. Although the planned matrix includes a sample with [REDACTED]% LDPE, this sample was not made. Thus the samples tested had 0%, [REDACTED]%, [REDACTED]% or [REDACTED]% LDPE. There were various proportions of [ADDITIVE A]/[ADDITIVE B]/ [ADDITIVE C].
125.	Document 52 is a report on this trial dating from June 2007. This begins with an executive summary, which records that the objectives of the trial were “manifold” and included four different objectives, one of which was “Adjusting the migration speed of PBO and DM in a monofilament polyethylene yarn by changing the HDPE/LDPE ratio and by exploring two different yarn diameters”. It then says that the results gave answers to these questions which included the following:
“An HDPE/LDPE ratio of [REDACTED] gives a [REDACTED] mm diameter yarn with good migration properties, albeit perhaps a tad slow. A ratio of [REDACTED] is difficult to extrude. It is possible that the optimal ratio be slightly underneath [REDACTED], i.e. perhaps [REDACTED].”
126.	The “results and main findings” include the following:
•	“The migration speed of PBO and DM in a monofilament polyethylene yarn is very sensitive to the type of polyethylene.  In HDPE, DM and PBO do not migrate. In LDPE, they migrate too fast. An HDPE/LDPE ratio of [REDACTED]seems like a good compromise between the issue of migration speed and that of physical integrity of the yarn. Some subsequent trials could include a ratio of [REDACTED], but probably not further.
•	The yarn diameter seems to have a great impact on the migration speed of DM and PBO, with [REDACTED] mm yarn demonstrating better migration than [REDACTED] mm. Despite of the largest reservoir in the latter case, it is possible that the bulk of the polymer matrix to be crossed by the migrating ingredients be too important.”
127.	The Defendants rely upon this Document as supporting the submissions they make in reliance upon the earlier Documents. In my judgment it gets them no further forward. I would add that the statement “In HDPE, DM and PBO do not migrate” is simply wrong if it is understood as meaning “do not migrate at all”: as the data in the Documents show, they do migrate to some extent.     
R16 trial (June 2007)
128.	This trial used a piston spinning system, which is a different technology from the screw extruder that was normally used. After Mr Howe had cautioned against comparing this data with data from screw extrusion trials in his fourth report, Professor Stevens abandoned reliance upon the results altogether.
R25 trial, Phase I (October 2007)
129.	This was a trial of seven formulations. The recipes included [REDACTED]% or [REDACTED]% LDPE, and three different sets of concentrations of [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C]. Four samples included PBO and three did not.
130.	Document 62 is a report on the trial dating from October 2007. It suggests that the trial was mainly concerned with various production issues. 
131.	Document 63 and 92 appear to be successive versions of another report on the trial with an “initiated date” of 23 October 2007, with Document 92 being the more complete. These documents include retention data and discussion thereof. Page 7 of Document 92 states:
“[REDACTED]”
132.	Very little is said in these Documents about the effect on deltamethrin migration of LDPE or of [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C]. The most one gets is that the conclusions at the end of Document 92 include the following:
“3.	[REDACTED]
4.		Recommendation for the next scale up production
(i)	Remove LDPE completely in order to slow down the migration
…. ”
R25 trial, Phase II (May 2008)
133.	This was a trial of eight formulations. All the recipes contained the same amounts of deltamethrin and PBO. LDPE was included at [REDACTED]%, [REDACTED]%  and [REDACTED]%. The recipes included constant amounts of [ADDITIVE A] and [ADDITIVE B] and varying amounts of [ADDITIVE C]. Two [REDACTED] were also included at various concentrations.
134.	Document 79 is a report on the trial dating from May 2008 which describes the goal of the trial as follows:
“Explore the impact of [REDACTED] on the storage stability of DM-PBO combi yarns, with and without [REDACTED]. Explore the impact of varying the LDPE contents on one known recipe.”
It appears from this Document that another goal was to try out a certain producer. 
135.	Bioassay and chemical assay data from this trial are contained in two spreadsheets, Documents 80 and 94. There was a good deal of evidence at the hearing about the data in Document 94, and again I will set out my findings below.
R25 trial, Phase III (July 2008)
136.	Again this was a trial of eight formulations. The recipes contained constant amounts of deltamethrin, PBO, [ADDITIVE A], [ADDITIVE B] and [REDACTED], but no  [ADDITIVE C]. LDPE was used at 5% or 10%. Varying amounts of [REDACTED] and [REDACTED] were also included.
137.	Document 81 is a report on the trial dating from July 2008 which describes the goal of the trial as follows:
“Confirm the impact of [REDACTED], especially at high levels of [REDACTED], on the storage stability of DM-PBO combi yarns. Explore the potential of using [REDACTED] as a [REDACTED], for DM-friendly light stablization. Explore the impact of varying the LDPE contents on one known recipe, at two different levels of [REDACTED]. Compare fabrics made of different yarns in the same color, in terms of stability to Neon light.”
138.	The results are reported in Document 82 dated 21 July 2008 and Document 83 dated 18 August 2008. Both of these documents are concerned with the storage stability of formulations with [REDACTED] and loss of active ingredients to neon light. Accordingly the results are not relevant to the issues presently before me.   
Question (i): how strongly the migration rate of deltamethrin is affected by the addition of LDPE to the polymer mix
139.	Although question (i) is framed in very general terms, and covers addition of LDPE at any percentage, I remain of the view expressed in the remedies judgment at [11] that what matters is the effect of LDPE in the proportions used by the Defendants. In this regard, it should be noted that the first Netprotect formulations tested in October 2004 included [REDACTED]%, [REDACTED]%, [REDACTED]% and [REDACTED]%   LDPE (see the main judgment at [406]).  The recipes used in January 2005 had [REDACTED]%, [REDACTED]%, [REDACTED]% and [REDACTED]% LDPE (see the main judgment at [421]). Furthermore, some of the Defendants’ production runs of Netprotect did not include LDPE (see the main judgment at [529], [535] and [605]).
140.	My conclusion in the Disputed Paragraphs, based in particular on paragraphs 119-121 of Mr Howe’s third report, was that there was no evidence that the addition of LDPE in these quantities had an important effect on deltamethrin migration.    
141.	VF submit that the new evidence is entirely consistent with what they have always said, namely that: (a) in general terms, the addition of LDPE to a polymer matrix otherwise consisting of pure HDPE would be expected to increase the migration rate of deltamethrin, with higher percentages of LDPE having a greater effect than lower percentages; but (b) there is no evidence that the addition of LDPE in the quantities used by the Defendants (i.e. [REDACTED]% where present) has a significant effect on the migration rate. I accept that submission.
142.	Proposition (a) is common ground, and therefore I need say little about it. It is worth noting, however, that Professor Stevens accepted that some migration occurred in pure HDPE. Thus HDPE has sufficient amorphous phase to support diffusion. In general terms, the effect of adding LDPE is to increase the extent of the amorphous phase and hence the ability of an additive like deltamethrin to diffuse though the polymer matrix. 
143.	As for proposition (b), as I have already mentioned, the figure of 10% LDPE which eventually found its way into the PCT Application as the most preferred level of LDPE had its origin in the data plotted in the graph reproduced below paragraph 101 above. As discussed in paragraph 103 above, if one assumes a linear relationship between LDPE concentration and deltamethrin retention, then 10% LDPE would give a retention index of [REDACTED]%. That is not significantly different from the figure of [REDACTED]% for 100% HPDE, however. 
144.	The key trial on the effect of adding LDPE is the R12 trial. The data from this trial do not support the Defendants’ contention that the addition of about [REDACTED]% LDPE has a significant effect on deltamethrin migration. As Professor Stevens accepted:
i)	Samples PE1 ([REDACTED]% LDPE and deltamethrin) and PE5 ([REDACTED]% LDPE and PBO) do not have significantly different retention indices than the corresponding 100% HDPE R4/R7 samples.
ii)	By contrast, PE7 ([REDACTED]% LDPE and PBO) does have a significantly different retention index to PE5 ([REDACTED]% LDPE and PBO).
iii)	PE7 and PE8 behave very similarly, although PE7 has 30% LDPE and PE8 has 10% LDPE, apparently because the difference in LDPE content is counteracted by the fact that PE8 has roughly double the PBO concentration to PE7.
145.	Professor Stevens’ critical level theory was based in large part on his analysis of storage stability data from the R25, Phase II trial contained in Document 94 in Figures 9-12 of his fourth report and the accompanying text. Since Professor Stevens did not support this theory in cross-examination, it is not necessary to go into great detail about this. It may be noted, however, that, as Professor Stevens accepted:
i)	Professor Stevens’ analysis was based on five samples: R64 and R93 (0% LDPE), AY7 ([REDACTED]% LDPE), AY2 ([REDACTED]% LDPE) and AY8 ([REDACTED]% LDPE). But AY8 must be treated with caution, because the recovery data for this sample were abnormally low for no apparent reason. Worse, R64 and R93 are not comparable with AY7, AY2 and AY8, since R64 and R93 were reference samples containing no [REDACTED] whereas AY7, AY2 and AY8 did include [REDACTED].
ii)	Figure 11 contained the wrong data, since Dr Herman had plotted [ADDITIVE B] retention data rather than PBO retention data.
iii)	If one compares the AY7 data ([REDACTED]% LDPE) with the AY2 data ([REDACTED]% LDPE), there is no appreciable change in the retention of deltramethrin.
146.	Finally, I would add that it is my understanding that both VF and the Defendants have experimented with the addition of LDPE (and other types of polyethylene) to the polymer matrix at various times for at least one reason other than its potential effect on deltramethrin migration, namely in order to make processing of the polymer easier.        
Question (ii): how that effect (if any) compares to the effect of [[ADDITIVE A], [ADDITIVE B] and [ADDITIVE C]]
147.	It was common ground between the experts in their reports that the experimental data contained in the Documents do not enable an analysis to be made of the effect of [ADDITIVE A], [ADDITIVE B] and [ADDITIVE C] on deltamethrin migration. Still less do they enable any conclusion to be drawn as to the relative effects of LDPE on the one hand and [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C] on the other hand. As discussed above, in his fourth report Professor Stevens advanced for the first time the theory that there had to be a critical level of LDPE present in order for the other additives to have a significant effect on migration, but this theory did not survive cross-examination.
148.	Accordingly, the new evidence does not provide me with any reason to revise the findings in the main judgment, which may be summarised as follows:
i)	[ADDITIVE A] acts, and was known to Dr Skovmand to act, as a migration enhancer: see [224], [243], [251]-[252], [277]-[278], [297], [352], [407], [514], [551] ;
ii)	[ADDITIVE C] acts, and was known to Dr Skovmand to act, as a migration inhibitor: see [224], [352], [407], [514];
iii)	The effect of [ADDITIVE A] can be seen even in a polymer matrix containing [REDACTED]% LDPE, which is one reason why Dr Skovmand reinstated it after experimenting with its removal from the Fence 65.F.0503.5 recipe (which contained [REDACTED]% LDPE) as Ciba had recommended, the other being its UV protective effect: see [290], [297], [551], [608]. Apart from that, the relative effect of LDPE on the one hand and [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C] on the other hand on deltamethrin migration is unknown. 
Question (iii): whether the outcome of issues (i) and (ii) above renders the Fence results not useful for the formulation of the Defendants’ product
149.	In the light of my answers to questions (i) and (ii), the answer to this question is no. On the contrary, I see no reason to revise my findings in the Disputed Paragraphs. Still less do I see any reason to revise my other findings in the main judgment.
Conclusion
150.	I conclude that the answers to the three questions of fact remitted by the Court of Appeal are follows:
i)	In general terms, the addition of LDPE to a polymer matrix otherwise consisting of pure HDPE would be expected to increase the migration rate of deltamethrin, with higher percentages of LDPE having a greater effect than lower percentages; but there is no evidence that the addition of LDPE in the quantities used by the Defendants (i.e. [REDACTED]% where present) has a significant effect on migration rate.
ii)	[ADDITIVE A] acts, and was known to Dr Skovmand to act, as a migration enhancer. [ADDITIVE C] acts, and was known to Dr Skovmand to act, as a migration inhibitor. The effect of [ADDITIVE A] can be seen even in a polymer matrix containing [REDACTED]% LDPE. Apart from that, the relative effect of LDPE on the one hand and [ADDITIVE A]/[ADDITIVE B]/[ADDITIVE C] on the other hand on deltamethrin migration is unknown.
iii)	No.