England and Wales Court of Appeal (Civil Division) Decisions

IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
THE TECHNOLOGY AND CONSTRUCTION COURT
His Honour Judge Boggis QC

		Royal Courts of Justice Strand, London, WC2A 2LL Friday 21 December 2001

Lord Justice Clarke:

Introduction

1. This is an appeal from an order of His Honour Judge Boggis QC made in the Technology and Construction Court in Birmingham on 31^st January 2001 in which he dismissed the claimant's claim after the trial of an action. He refused permission to appeal but permission was subsequently granted by Mance LJ on 3^rd April 2001.

The Claim

2. The appellant ("Watsons") was the sub-contractor under a contract with a main contractor called Galliford who in 1998 had agreed to build a large rail freight terminal at Daventry. Watsons in turn sub-contracted certain plumbing works to the respondent's firm Mercia Plumbing and Heating ("Mercia") which is a firm of plumbers run by David Howard and his son Colin.
3. Although there was an issue between the parties as to the precise terms of the sub-contract, it was common ground at the trial that it provided for Mercia to install on a labour-only basis a 110mm water pipe along both sides and across one end of a warehouse. The pipe was to serve the fire hydrant system. The total length of the pipe was about 750m.
4. It was also common ground that it was an implied term of the contract that Mercia would use reasonable care and skill in carrying out the installation work. Watson's case was that Mercia were in breach of that implied term and that, as a result, there were so many leaks that the pipe had to be abandoned and a new pipe installed by other plumbers. The essence of the alleged breach was that Mercia failed to prepare the pipe properly. Watsons put its claim for damages as £61,013.94 less a balance of £8,396.37, which was due to Mercia under the sub-contract, leaving a net claim of £52,617.57. Part of the claim was also put as a claim for an indemnity under a term of the sub-contract. In addition Watsons advanced a separate and independent claim of £6,709.00 which they said was due under a separate collateral contract under which Watsons supplied Mercia with additional labour to carry out the works.

The Judgment

5. The judge held that Mercia were not in breach of duty so that the claim for failed. He said that in those circumstances no question of quantum arose, although he made some findings at least which were adverse to Watsons. For some reason he did not deal with the further claim for £6,709.00 at all.

Issues on Appeal

6. The issues on appeal can be considered under three heads, namely breach of contract, quantum and the further claim.

Breach of Contract

7. The judge posed the question: why did Colin Howard's pipe leak? He rejected Watson's answer to that question which was that the pipe leaked because of lack of proper preparation by Colin Howard. He said:

" on the balance of probabilities, I am not satisfied that the leaks were the result of poor preparation".

He added:

"in my judgment the evidence points towards a failure in the material supplied by Watsons, ie that the pipes and couplings were not compatible, or at least that they had a loose fit which demanded the use of clamps to ensure absolute stability whilst the fusion process took place".

8. The first and most important issue on this appeal is whether the judge was wrong to reach those conclusions. Watsons have been represented on this appeal by Mr Adrian Williamson, who did not appear below, and who has advanced the appeal before us with admirable clarity. His principal submission is that the judge's conclusion as to the cause of the leakage was wrong. His main argument is that it was common ground between the parties' experts that it was "almost certain" that lack of preparation was the cause of the leakage, that the experts discounted incompatibility as a cause and that the judge should not have espoused it.

The Work

9. I can take the description of the pipe and the work largely from the judgment. The pipe is made of polyethylene. As constructed, it comprised pipe of two wall thicknesses, namely medium density polyethylene (or MDPE) and high pressure polyethylene (or HPPE). Where the pipe was to be jointed, as for instance in order to join two lengths together, or to take off a T, a coupling was used. This was a separate piece into which the pipe fitted. The coupling had a copper wire wound round each socket. When the pipe had been inserted, an electrical fusion machine was connected to a terminal built into the socket and a current was passed through the copper wire for a specified number of seconds. In the present case, it was 200 seconds. The wire was heated up by this process and melted both the plastic of the socket and the part of the pipe immediately underneath the wire. The two then melted or fused together.
10. When the melting process had been completed, a small amount of melted plastic was expelled from a small moulding on the outside of the coupling, to show that the heating process had been completed satisfactorily. The pipe and socket had to be held together immobile while the fused plastic cooled down. Again this was for a set time, namely 10 minutes in the present case. This procedure has a good reputation for reliability. However, the makers are insistent on very careful preparation of the joint to be fused.
11. The correct procedure involved or should have involved three separate actions. First, the end of the pipe which goes into the socket of the coupling must have the oxidised layer of plastic removed from the area which will be fused. The best (and recommended) way of doing this is to use a mechanical scraper which removes a thin piece of plastic from the end of the pipe, having a thickness of between 0.2 and 0.4mm. This shaving is removed as a continuous piece of swarf . Alternatively, the oxidised layer is removed from the end of pipe by scraping the pipe with a manual scraper. Again, the scraping needs to remove between 0.2 and 0.4mm. The scraping will be done by pulling the scrapper in the direction of the pipe. The scrapings must all join up so that the oxidised layer is removed all the way round the end of the pipe.
12. Although, as the literature shows, manual scraping is a more difficult and potentially less successful method of removing the oxidised layer than mechanical scraping, it was not suggested at the trial or before us that Mercia could not achieve a satisfactory result by manual scraping provided only that the scraping was done with reasonable care and skill.
13. The second part of the preparation is that, once the pipe end is scraped, it should be wiped clean with a purpose made wipe or with a clean lint free rag. The inside of the socket should also be wiped. Finally the third stage is that the pipe should be clamped in the coupling with purpose made clamps, so that the joints cannot move while the fusion process takes place and the pipe cools down. The judge described the respective roles of Mercia and Watsons as follows:

"Mercia was employed on a labour-only contract. They provided the skilled workman, in this case Colin Howard, and the necessary hand tools. Watsons provided the materials and the necessary plant. It is common ground that the fusion machine was plant, and I am satisfied that the clamps were also plant. David Howard told me that the clamps came with the fusion machine in his experience, and I accept that evidence".

14. There was an issue at the trial as to who was responsible for doing what, to which I shall turn in a moment, but it is common ground that all the preparation work was done by Colin Howard using a Stanley knife and that clamps were not used at all. The first and most important issue on this appeal is whether the leakage which occurred was caused by poor preparation on the part of Colin Howard or some lack of compatibility between the pipes and the sockets. However, before considering that issue, it is I think important to say a word about the witnesses and the judge's approach to them.

The Witnesses

15. The trial followed a somewhat unusual course, which may not be without significance. Watsons first called two witnesses of fact to give oral evidence. They were Mr Darren Bradbury and Mr Gerald McNally. Mr Bradbury was a building services engineer engaged by Watsons and Mr McNally was Watsons' labour manager. The judge said this with regard to their evidence:

"In my judgment, Mr Bradbury was completely out of his depth in his role as engineer for Watsons on this project. He was very young, only twenty-four. He had very little experience, he was under time constraints. He wanted Colin Howard to do the best he could and get on with the pipe line despite all the concerns as quickly as possible. I am satisfied that he was completely unsupported by his superiors

Mr McNally was a bluff labour manager. He clearly held the sub-contractor wholly responsible. I could not discern from him what was the role of Watsons, other than to lay blame away from themselves."

16. Those views are to be contrasted with the conclusions which the judge reached as to the evidence of David and Colin Howard. In that regard he said this:

"Save for one point, Colin and David Howard gave their evidence in an honest and believable way. The one point is that in paragraph 8 of his witness statement, Colin Howard says this:

"The removal of the top layer of the plastic helps to ensure that the fusion takes place properly. The manufacturer provided a specialist scraper for this purpose and when I asked Darren Bradbury to provide me with a scraper, he said a hand scraper was good enough to prepare the pipe. Consequently I was forced to use a Stanley knife to prepare these pipes, which was not the ideal tool for the job".

That was not his oral evidence. His oral evidence was that he was perfectly happy to use the back of a Stanley knife because that is the way he had done it the past, when the purpose made mechanical scraper was not available.

In my assessment of Colin and David Howard, I have expressly taken into account the fact that that part of his witness statement is clearly wrong. Colin and David Howard are working plumbers. They voiced their concerns, and even wrote some of them down. My finding, even taking into account paragraph 8 of Colin Howard's statement, is that they were honest witnesses in the witness box, and I prefer their evidence where it differs from that of the claimant's witness, except so far as the provision of the scraper was concerned".

Mr Brunt (who appeared for Mercia before us as he did before the judge) places considerable reliance on those conclusions.

17. Apart from Mr Bradbury and Mr McNally, the only other evidence of fact adduced by Watsons was a witness statement from their managing director Mr John Watson. His evidence is not directly relevant to the cause of the leakage.
18. After Mr Bradbury and Mr McNally had given oral evidence, Watsons called their expert, Mr P Stonard, and Mercia called their expert, Mr A Johnson. I shall return to their evidence below but the judge was not impressed by either of them. He said:

"Neither expert inspired any confidence at all. They both overlooked or discounted the significant fact that the leaks were confined to the area where mixed pipes and couplings were used. They simply said that the manufacturer spoke of compatibility, but they undertook no tests at all to confirm that assertion".

19. For some reason the oral evidence of Colin Howard and David Howard was given only after the experts had both given evidence. Mr Williamson pointed out that some of their evidence covered aspects of the facts not addressed by the earlier witnesses. That is I think so but counsel then appearing for Watsons did not seek to adduce further evidence to fill any perceived gaps, although he could have done so, and, in my judgment, the judge was entitled to proceed on all the evidence before him.
20. In examining the reasons given by the judge for reaching his conclusions it is, in my judgment, important to have in mind the views which he formed of the witnesses. It is well settled that this court will not lightly interfere with findings of fact which depend to any significant extent upon the conclusions of a trial judge as to credibility, where the judge has had the advantage of seeing the witnesses and hearing their oral evidence. However, before turning to the judge's conclusions on the evidence and to the attack mounted upon them, it is convenient to refer to the terms of the contract in order to put the respective roles of Watsons and Mercia in their proper context.

The Contract

21. At the trial, initially at least, it was Watsons' case that the contract between Watsons and Mercia was evidenced by three documents, namely a manuscript purchase order, a two-page printed document entitled "Conditions of Installation Sub-contract (JWS-01)" and a two page typed document which bears the date 14/03/97 and is entitled "John Watson Services Ltd, Conditions/Terms for labour only price work contracts". It was common ground that the two page printed document, which I shall call "the JWS/01 document" was part of the terms of the contract but there was an issue as to whether the typed document was also incorporated.
22. The significance or potential significance of this point is that the typed documents includes the following:

"The labour only contractor shall:

…

(8) Provide all necessary tools and plant such as: hand tools, leads, transformers, task lighting, safety boots, gloves, hats, goggles, ear defenders, overalls etc. Also steps, trestles, access equipment, welding equipment, fire extinguishers, screwing machines, pipe benders, site boxes etc. If specifically agreed in writing certain plant may be hired to contractor at a reasonable weekly rate".

23. It was Watsons' case that by clause 8 it was Mercia's contractual obligation to provide both tools and plant and that that plant would plainly include, for example, clamps even if clamps were not tools. It is, I think, reasonably clear that the judge did not treat the typed document as incorporated because of the passage which I have already quoted in which he described Mercia as providing the necessary hand tools and Watsons as providing "the materials and the necessary plant", which he found included or was intended to include clamps.
24. Mr Williamson invited this court to hold that the typed copy was part of the contract. He relied both on Mr Bradbury's statement and his oral evidence. In his statement Mr Bradbury said that he personally signed the purchase order. He added that the "order contains the works to be carried out by Mercia and incorporates JWS Conditions of Installation Sub-contract (JWS/01)". A little later he wrote:

"It was also a term of the contract (at clause 8 of JWS/01) that Mercia provided their own tools for the job, which again is standard practice".

The problem with that statement is that clause 8 is not part of JWS/01 but part of the separate typed document.

25. It is also to be noted that the hand-written purchase order signed by Mr Bradbury sets out the services to be carried out by Mercia "in accordance with the following documents". The "following documents" include "(e) conditions of installations sub-contract (JWS/01) Pages 1 & 2". They thus include the two-page JWS/01 document but make no reference to the typed document. The inference from those documents would thus be that the typed document was not incorporated.
26. When that was put to him in cross examination and it was suggested that he did not hand the typed documents to Mr Howard, Mr Bradbury said:

"I believe I did 'Yes'".

There then followed this exchange:

"Q. If you had've done, we'd know. You'd have written it on there. You've been meticulous.

A. I know I have, Yeah. 'Yes'".

That answer is perhaps ambiguous. Mr David Howard said in evidence that he was not sure.

27. In that state of the evidence, as I read the transcript of the final submissions made by Mr Townend (who appeared for Watsons at the trial), he conceded the point. I can well understand why he did so given the absence of any reference to the typed document in the manuscript purchase order and the uncertainty of the evidence to which I have referred. In these circumstances, the judge was in my opinion justified in approaching the case in the way he did, namely on the basis that the typed document was not incorporated into the contract.

The Findings of the Judge

28. Colin Howard gave evidence which, as I have indicated, (with one exception) the judge accepted. He started work late in 1988 and first laid the pipe at the end of the building, which was much shorter than the sides. Watsons did not supply any clamps. Nor did they supply scrapers, but the judge held that it was for Mercia to supply scrapers as part of the necessary hand tools. In fact Colin Howard carried out hand scraping using the back of a Stanley knife blade, which he was quite willing to use. As I read his judgment, the judge accepted Colin Howard's evidence that, while leaks are always a potential problem with any plumbing, he had had no particular problems with this type of pipe or fusion process.
29. The judge described this part of Colin Howard's evidence in this way:

"Colin Howard did tell me, however, that he was concerned that having put in the first run of pipe he found it had been back filled and concreted over by the main contractor, without any reference to him. He told me that he wanted the joints exposed whilst he tested, so that leaks could be seen and repaired. He told me that he raised his concerns with Watson's engineer, Mr Bradbury. Mr Howard told me that Mr Bradbury's response was first that time was tight and the main contractors had to get on with the job and secondly that fusion joints do not leak anyway.

Having completed the first run, Mr Howard then ran out of some of the materials. Mr Bradbury told me that the pipe being installed was not the most popular size, and so he had to get materials from a different supplier. Colin Howard told me that when he started working with the new materials, he immediately voiced his concerns to Mr Bradbury. He was concerned that he now had two types of pipe, both medium density and high pressure, and further, the pipe and the couplings came from different manufacturers.

He told me that in places, he could get a hacksaw blade between the pipe and the socket. When he had laid the first short run, he had used only medium density pipe and sockets made by the same manufacturer as the pipe. His evidence was that when they ran out of materials and fresh materials were supplied when he started the long run, at that point he had pipes that were both high pressure and medium density, and he had sockets and the pipes and the sockets came from different suppliers.

Mr Bradbury confirmed that Mr Howard did indeed raise these concerns with him. Mr Bradbury reported them to his superior, Mr Knight. Mr Bradbury told me that he had no experience to comment on the fit of the pipes. He told me that he thought they seemed a bit loose, but that he was in no position to pass an expert view over the fit. He simply did not have the experience of this sort of work. He simply reported the matter to his superior.

He also told me, and this was confirmed by Mr McNally, Watson's labour manager, that arrangements were made for a supplier's representative to come to the site. Mr Smith, of Fusion Provida, who I understand to be the makers of the couplings, came to the site and apparently said that the pipes and fittings were compatible. I have not heard from Mr Smith in evidence.

Despite Mr Bradbury's lack of experience, he does nevertheless seem to have had the authority to decide to replace a medium density pipe with a high pressure pipe, which is all that he could get.

Mr David Howard was still sufficiently concerned to write to Mr Bradbury by a letter dated 25^th January 1999 saying that the pipes were of different grades, and from different manufacturers, and did not give a tight fit in the sockets. He said that his firm could not be held responsible for any leaks. There is doubt about whether this letter was sent or received. I am satisfied that it was both sent and received."

30. I have set out that part of the judge's account of the evidence in some detail because (as I read his judgment) he accepted it and it played a crucial part in his reasoning. In particular, the judge was impressed by the fact that it was only after new materials were obtained that problems began to arise. In particular, it was at that time that Colin Howard said that he could get his hacksaw blade between the pipe and the socket. It appears that the judge thought or may have thought that that was or may have been caused by using different density pipe and/or by using pipe and couplings from different manufacturers. That Colin Howard complained to Mr Bradbury was confirmed by Mr Bradbury himself, who thought that the pipe and couplings seemed a bit loose. Although Mr Bradbury was not an expert, his evidence confirmed Colin Howard's evidence that the pipe and sockets, or couplings, were not a tight fit or (as it was described in some parts of the evidence) snug.
31. It appears that the judge discounted the opinion of Mr Smith of Fusion Provida, who were the makers of the couplings, because he did not hear from him in evidence. In fact Mr Smith neither provided a written statement nor gave oral evidence. In these circumstances the judge was entitled to pay little regard to his views.
32. The judge was impressed by the fact that on 25^th January 1999, which was during the work, Mercia wrote a letter to Watsons in these terms:

"As discussed on site, we would like to confirm our concerns regarding the pipe used on the above contract.

The various types of pipe being used are of different grains and of different manufacture.

The fitting of these types does not seem to give a tight joint and we cannot be held responsible for any leaks that may occur due to this mis-match".

The judge expressly held that the letter was sent and (contrary to Watsons' case at the trial) received at the time. In my judgment, the judge was entitled to be impressed by the letter as setting out Mercia's genuine concerns at the time, especially since there is no other contemporary document produced by either side (including Watsons) which helps to identify the state of mind of those on site during the work. The letter is important because it expressly makes the point that the pipes did not make a tight joint, presumably with the couplings.

33. The judge held that, despite his complaints, Colin Howard was told to proceed with the job, which he did. The judge also pointed to Colin Howard's evidence that he wanted to test the pipe in sections but was told that the job had to be done quickly and to his further evidence that throughout the continuation of the job the trenches were back filled with concrete without any reference to him. The judge concluded his account of Colin Howard's evidence as follows:

"It is significant however, that the uncontradicted evidence of Colin Howard is that all the leaks were in the pipeline manufactured piecemeal, with pipes and couplings from different suppliers."

It is plain that the judge was impressed by Colin Howard's evidence and formed the view both that he was telling the truth and that he was not mistaken when he said that the problems they were having were due to poor fit between the newly obtained pipes and couplings. If the only evidence before the judge had been the evidence of Mr Bradbury, Mr McNally and Mr Watson for Watsons and the two Howards for Mercia, I can see no sensible basis upon which his conclusions could be challenged, let along reversed, in this court.

The Expert Evidence

34. However, the main thrust of Watson's attack on the judgment depends upon the judge's treatment of the expert evidence. All or almost all of the grounds of appeal rely upon the expert evidence and assert that the judge should not have held that it was not reliable. In particular, in a compelling argument Mr Williamson submitted that the judge should have accepted the joint view of both experts that the leakage was not caused by any incompatibility between the pipes and the sockets but by poor preparation on the part of Mercia.
35. There is considerable force in Mr Williamson's submissions because it must be a rare case indeed in which a judge can properly disregard all the expert evidence in the case, especially when it is to the same effect. The strength of the argument in the instant case can I think be seen from the following. Watsons sent four sections of pipe to BSRIA Ltd to be tested. Each section consisted of both pipe and couplings. BSRIA was asked to try to establish the cause of leakage. It entrusted the work to Mr Stonard, who concluded that three of the four sections leaked at the joint and concluded:

"Pipe preparation did not look to be adequate on those items that had failed. Some pipes had external markings visible in areas that should have been scraped clean."

36. He gave some consideration to other possible causes and, according to the BSRIA report, which he wrote, he expressed these conclusions. It was not thought that the materials were likely to be faulty, the labelling was clear and unambiguous, the sizes and pipe types were as specified in the manufacturers' literature, the overheating in one area could have been caused by incorrect time setting or faulty equipment and he was unable to comment on the electrical elements prior to use or on pipe clamping or storage. His conclusion was expressed as follows:

"It is considered most likely that the faults were due to departures from manufacturer's procedures when installing the items on site, particularly with regard to joint preparation".

As I understand it, Mr Stonard did not consider Mr Howard's account of what he had done, but simply expressed his opinions based on his examination of the four sections of pipe and coupling which he was sent. He took some photographs of them which were available to the court.

37. Mr Johnson was instructed as an expert by Mercia. His expertise was very different from that of Mr Stonard. He was (and no doubt is) a technical training consultant. He made a report in which he described in some detail the correct method of jointing polyethylene pipes using electro-fusion. It is by no means clear what information was provided to him, but on the basis of whatever it was he expressed the view that Watsons did not provide a mechanical scraping tool or suitable clamps. He also expressed some doubts about the electro-fusion control boxes and about the method of testing the work. In his report, he expressed his brief conclusion thus:

"In conclusion I would suggest that Mercia … are not blameless for the bad jointing practices. However given that … Watsons … did not supply the correct tools and equipment to complete the work, in accordance with industry standards, Mercia … probably did the best job they could, given the circumstances. Add to that the fact, that back filling the trenches before any kind of proof test was completed, no matter how short a length, all amounted to the pipeline failing before it was commissioned."

38. Mr Stonard and Mr Johnson subsequently met on 20^th October 2000. They considered a number of specific questions. Their views can be seen from the answers they gave to a number of points which were put to them:

"Point 1. The possible causes of leaks are lack of pipe preparation, lack of clamping, faulty control boxes.

Point 2 to 3.4. Of the above items in relation to the pipe samples examined, the degree of certainty in this instance is as follows. Lack of preparation – almost certain. Lack of clamping – possible. Faulty control boxes – unlikely.

Point 4. The degree of risk of leaks caused by inadequate preparation is very high.

Point 5. The procedure for manual connection of fusion pipes and reason for procedures are detailed but well known and we would refer to the Water Industry Specification WIS 4-32-08.

Point 6. The reason for scraping the pipe is to remove a layer of oxidised pipe. The use of a scraper may as an additional benefit remove surface contamination, but that is not the reason for scraping the pipe.

Point 7. The presence of the raised melt indicators on the samples examined indicated the heating/cooling cycle had been completed. This would indicate the control equipment had run for the appropriate time and to the appropriate temperature.

Point 8. There is no evidence to suggest a proper site pressure test was or could be carried out due to lack of collated test data and substantial leaks on site. The site tests and laboratory tests at BSRIA were separate and there cannot be correlation between the two since the site test procedures were not witnessed by the experts appointed.

Point 9. The technique of pipe scraping is an elementary technique. However, a plumber may not be aware of this system, whereas we would expect a pipe layer or specialist contractor should be. The definition of a plumber would need clarifying.

Point 10. It is standard practice to test pipelines and joints before backfilling. Pipe runs may be backfilled but joints should be left exposed. Any length of pipe may be tested with the proviso that adequate and sufficient equipment is used for the size of the job being tested. The procedure is relatively simple subject to the proviso above.

Point 11. Yes, one of the purposes of using PE pipe is to allow long lengths of pipe to be run, thus minimising the number of joints.

Point 12. Mechanical scrapers can be divided into two types: simple hand scrapers and others that fit onto the pipe and remove a continuous strip of material to the required depth. Hand scrapers are cheap and it would be expected that a pipelayer or specialist contractor would have such an item. They would not necessarily possess other types of scrapers as they are relatively expensive, the size and type available being matched to different ranges of pipe diameters.

Point 13. Tools should have been available prior to the job commencing as per the contractual arrangements between John Watson and Mercia. Concreting over should only have been carried out after a successful pressure test. The technical procedures followed during the job should have been those given in WIS 4-32-08 Issue 2: 1994.

In conclusion, Andy Johnson and Philip Stonard believe that the most likely cause of the pipeline failure was lack of preparation of the pipe. The use of a pressure test prior to backfilling would have revealed any jointing problems, with the possibility of rectification before concreting over."

39. Watsons naturally relied upon that agreement both at the trial and before us. It undoubtedly provides strong support for the case that the leakage was caused by poor manual preparation by Mercia and thus for Watsons' case. Mr Williamson also relied upon the oral evidence of the experts and upon the way the case was approached by Mr Brunt on behalf of Mercia at the trial. Both experts supported the views expressed in their agreement at the trial and Mr Brunt prepared written submissions on the assumption that the judge would accept that a cause of the leakage was poor preparation on the part of Colin Howard.
40. Thus Mr Stonard said in evidence that poor pipe preparation was the main reason for the failure. His view was that incompatibility was not a problem. In particular he assumed that pipes and couplings from different manufacturers would be compatible provided that they used the same British Standards, which they did. He also saw nothing which suggested that that was not the case and found what he perceived to be the cause of the problem, namely leakage in the pieces of pipe which he examined, which had not been properly prepared. Mr Johnson gave evidence to similar effect. Thus he acknowledged that he had agreed with Mr Stonard that he was almost certain that lack of preparation was a cause of the leaks. He said that he had reached that conclusion on the basis of Mr Stonard's report, which he had read before they met. He also said that incompatibility was not generally an issue or problem.
41. The judge was not impressed by the expert evidence, to which I shall return below. He expressed his conclusions in this way:

"Neither expert inspired any confidence at all. They both overlooked or discounted the significant fact that the leaks were confined to the area where mixed pipes and couplings were used. They simply said that the manufacturer spoke of compatibility, but they undertook no tests at all to confirm that assertion.

On the balance of probabilities, I am not satisfied that the leaks were the result of poor preparation.

In my judgment, the evidence points towards a failure in the materials supplied by Watsons, in that the pipes and couplings were not compatible, or at least that they had a loose fit which demanded the use of clamps to ensure absolute stability whilst the fusion took place.

My finding is that Mercia raised this concern at the time but the Watsons did not take it seriously. It follows that the claim fails at the liability stage. "

42. The judge preferred the evidence of Colin Howard to that of the experts. He was not impressed by the experts' evidence, partly I think because of their limited expertise, one as a laboratory manager and the other as a technical training consultant, and partly because he formed the view that neither of them had given sufficient consideration to the possibility that the cause of the leakage was some kind of incompatibility between the pipes and the couplings.
43. The judge said of Mr Stonard's evidence about the possibility of incompatibility:

"He said that so far as the issue of compatibility was concerned, he discounted this because the manufacturers said in their various brochures that their products were compatible with other makers' products."

As to Mr Johnson, he said this:

"Mr Johnson was asked about the compatibility problem. He said that he did not consider that the identity of the manufacturer was an issue, because the fittings were were approved to BSI tolerances.

However, he also said that in the light of this case, there might be a serious issue for the industry because the manufacturers do not guarantee their products to be compatible with those of other manufacturers. Mr Stonard told me that he had not inspected unused pipes and couplings from different manufacturers in the course of considering his evidence."

44. Mr Williamson submitted that the judge should not have rejected the agreed expert evidence that the cause of the leakage was failure to prepare the pipe correctly on the part of Mercia. He pointed to the fact that the judge does not explain why he rejected Mr Stonard's evidence, which was based on work done in the laboratory on specimens taken from the part of the pipe which was leaking and from the part of the pipe where new pipe and couplings were used. There is, in my judgment, considerable force in that submission. The judge should have given his reasons for rejecting that evidence as sufficient evidence of the cause of the leakage.
45. On the other hand, the judge was not bound to reject the evidence of Colin Howard and accept the agreed evidence of Mr Stonard and Mr Johnson. The judge must, I think, have concluded that any leakage found to exist in the specimens tested by Mr Stonard was not the cause of the problems identified by Colin Howard. It is I think evident from the questions asked by the judge in the course of the evidence and submissions that he formed the view that the experts did not sufficiently consider whether the pipes were in fact incompatible. For example, after Mr Stonard had said that he found that there had not been any or any sufficient scraping and that that led him to adopt a particular train of thought, namely poor preparation, there followed this exchange between the judge and Mr Stonard:

"Q. Well, isn't that a cart and horse problem, that it may be that there was no scoring or something like that, but it may also be that the scoring was wholly irrelevant if the two things were not properly compatible in the first place.

A. Again, I can only say from the manufacturer's literature and the water industry specification guide, that looking at the information in that, we didn't consider that to be an issue.

46. It seems to me to be reasonably clear from Mr Stonard's evidence that he recognised that loose fitting or incompatibility of the pipes and the couplings was a theoretical possibility, but did not think that it was the cause because of the poor preparation which he found in three of the four joints he was sent. However, the reason that the judge did not accept that it was shown that poor preparation was the cause of the problem was that he did not think that incompatibility had been sufficiently considered by Mr Stonard, who had inferred from the four specimens he examined that the whole problem was leakage caused by poor preparation.
47. As to Mr Johnson, he did not see either the pipe itself or the specimens, but only photographs of the latter. When asked about possible problems with pipes fitting together, he said that it was not generally an issue because all the pipes and fittings are approved by (or to) the water industry specification and made to the appropriate British Standard; so that they should all be, as he put it, of reasonable tolerances. He also said that the absence of clamps might be a problem.
48. As I indicated earlier, it was only after the experts had given evidence that the judge heard the evidence of the two Howards, but no-one suggested that either of the experts should be recalled. I have not found this an easy appeal in which to reach a conclusion on liability, but I have ultimately reached the conclusion that the judge was entitled to conclude that Watsons had not shown that poor preparation was the cause of the major leakage. He was entitled to accept the evidence of Colin Howard that the pipes did not fit together properly, supported as it was by a contemporary letter of complaint expressly referring to a mis-match. He was also entitled to accept Mr Howard's evidence that he could get a hacksaw blade between the pipe and the socket in the area where new pipes and couplings from different manufacturers were used. Mr Howard's evidence received some (albeit limited) support from Mr Bradbury, who was not an expert, but thought that the pipes seemed a bit loose. Moreover, Watsons did not investigate Mercia's complaints at the time, but, on the judge's findings (which are not to my mind open to serious challenge in this respect) covered the pipe with concrete before the work could be properly tested. That was of some significance because, as the experts agreed, it was standard practice to test pipelines and joints before backfilling. The result was that it was made more difficult for Watsons (or indeed Mercia) to identify the true extent and cause of the leakage.
49. The essential question is whether the judge was bound to reject Colin Howard's evidence because of the views of the experts. In my judgment he was not, although he should in my view have given express consideration in his judgment to Mr Stonard's evidence that three of the four sections sent to him leaked and that the leakage was caused by poor preparation. On the other hand no-one asks for a new trial, so that we must do our best with the material available. It seems to me that the judge was entitled to conclude that the evidence of the experts was of comparatively limited value and that it was not so strong as to require him to reject evidence of fact from a witness, Colin Howard, whom he plainly regarded as both a witness of truth and a reliable witness.
50. I do not think that the judge can have intended to reject Mr Stonard's evidence that three of the four specimens he was sent showed that there had been poor preparation. If he had, he should (and no doubt would) have said so expressly. Doing the best I can, I read the judgment as accepting the evidence of Colin Howard that the essential cause of the major problems which existed at the time was a poor fit or, put another way, incompatibility between the new pipes and couplings. He was not saying that the preparation was all up to standard but that the essential cause of the problem was that identified in the letter of 25^th January quoted above, namely incompatibility.
51. Although, as I have said, Mr Stonard in effect accepted in evidence that incompatibility was a possible cause of leakage, it was not one of the possible causes of leaks identified in point 1 of the experts' points of agreement. It is not clear why not, although the judge formed the view that the experts simply assumed that because the pipes and couplings were said to be manufactured to the same British Standards, albeit by different manufacturers, there would not be a problem. But, as the judge put it, they undertook no tests to confirm that assertion.
52. In all these circumstances, I have reached the conclusion that the judge was entitled to reach the conclusion that he did, namely that he was not satisfied on the balance of probabilities that the major leaks which caused the problems were caused by poor preparation, even though there was some evidence of poor preparation. In short it was open to him to hold that the evidence points, or at least also points, to a failure of materials supplied by Watsons, in that (as he put it) the pipes and couplings were not compatible.
53. He added an alternative possibility to the effect that the problem might be a loose fit which demanded the use of clamps to ensure absolute stability while the fusion process took place. However, neither party submitted that, if there was incompatibility, the potential problems could be solved by clamps. Thus the question is simply whether the judge was right to hold that the evidence pointed to simple incompatibility as the cause. In my judgment, he was.
54. I should add in this regard that he was not, as I read the judgment, rejecting the evidence that in principle pipes and couplings manufactured to the same British Standard should be compatible, as evidenced for example by a fax from Fusion Provida dated 21^st April 1999, but simply questioning whether they always are. It may be noted in this regard that, as it was put in a letter written by Mercia's solicitors after communicating with the manufacturers of the pipes and the couplings, while both manufacturers maintain that their products are interchangeable, they will not guarantee their own products if coupled with a product from another manufacturer. There is no reason to think that that letter does not faithfully reflect what the solicitors were told.
55. I do not think that this court could properly hold that the judge was not entitled to accept the evidence of Colin Howard and that the judge should have held that the cause of the leakage was a breach of contract on the part of Mercia. He was entitled to hold that Watsons had not shown that the cause of the leakage which gave rise to the problems was poor preparation as opposed to incompatibility of some of the pipes and couplings. It was not, so far as I am aware, part of their case that Watsons were able to recover if part of the problem was leakage from one source and part from another, no doubt because of difficulties of proof.
56. For these reasons, although I recognise the force of some of the submissions so clearly put by Mr Williamson, I would dismiss the appeal on liability. This conclusion is, I think, reinforced by some aspects of the debate on quantum, to which I turn briefly even though it does not strictly arise having regard to my view on liability.

Quantum

57. In this regard the judge said this, after concluding that the claim failed at the liability stage:

"It follows that I shall not have to consider the question of quantum, but I should make it clear that on the evidence I have heard, I am not satisfied that it was necessary to replace the whole pipeline.

Further, I am satisfied that the location of the leaks was made very much harder by the backfilling and concreting done by the main contractor. My finding is that Mercia wanted to test in sections whilst the pipes were uncovered, but was prevented from doing so through no fault of their own."

58. I see no sensible basis for reversing that conclusion. It follows that, as I indicated earlier, it was difficult both to locate the leaks and to identify the faults in pipeline because Watsons covered it in concrete. In these circumstances, there seems to me to be no injustice in holding that Watsons failed to establish their case on causation. It would also follow that, even if they established liability in principle based on the proposition that some of the leakage was caused by a breach of contract on the part of Mercia, they would not be entitled to recover in respect of a large part of the claim, which was for renewal of the pipeline.
59. Watsons also faced similar problems in so far as they tried to recover the amount of any liability to Galliford, the main contractors. It is clear that some part of Galliford's claim against them is comprised of losses or costs associated with the replacement of the pipe, which, on the view of the case which I have expressed above, would not be recoverable. Further, although Mr Williamson submitted with force that the quantum had been vouched by an expert witness, Mr Hart, whose evidence was not challenged on behalf of Mercia at the trial, his evidence to my mind did not establish that Watsons had agreed to pay any specific sum to Galliford. Nor did it establish the amount of its contractual liability to Galliford, whether by way of indemnity or damages.
60. Thus, even if it were established that all the leakage had been caused by breach of contract on the part of Mercia, the quantum of the claim would continue to present problems. It follows that, if it were concluded that some, but not all of the leakage was caused by such a breach of contract, the problems would be all the greater. However, in the light of the conclusions as to liability expressed above, it is not necessary to discuss issues of quantum any further.

The Further Claim

61. As indicated above, Watsons claimed a further sum at the trial of £6,790.00. That sum was claimed pursuant to a separate oral agreement under which Watsons said that they supplied Mercia with additional labour to carry out works under their contract for which Mercia had agreed to pay. I should note in this regard that the works to be carried out were more extensive than the laying of the pipe. The evidence clearly shows that such an agreement was indeed reached. It is not necessary to spell out that evidence because I understood Mr Brunt to accept that that was so.
62. As to quantum, it is not I think in dispute that, if Mercia are liable, the appropriate figure is that claimed, namely £8,149.02, including interest. The only suggestion that Mr Brunt was able to make in support of a submission that Mercia are not liable for that amount was that the further work had been necessitated in some way by the conduct of Watsons. However, no such general case was advanced at the trial and no particulars have been given of it and, in so far as it was suggested that problems with the pipeline might have been the cause, as Mr Williamson pointed out, the agreement relied upon by Watsons predated the leakage.
63. However that may be, the position is simply this. Mercia have failed to pay for labour which Watsons agreed to provide. Mercia were liable to pay for the labour unless they could show that the necessity for it was caused by some breach of contract on the part of Watsons. For some reason the judge overlooked this part of Watson's claim and it appears that no-one pointed it out to him at the time of judgment. In these circumstances Watsons' appeal on this point succeeds.

Conclusions

64. I have not found this an easy case, but for the reasons I have given, I have reached the conclusion that the appeal should succeed to the extent of £8,149.02 in respect of what I have called the further claim, but that it should otherwise be dismissed.

Mr Justice Wall:

65. For the reasons given by Clarke LJ, I also agree that this appeal should be dismissed save in so far as it relates to the sum of £8,149.02, which my Lord has designated "the further claim" in paragraphs 61 to 63 of his judgment.
66. Like Clarke LJ, I have not found this an easy case, and I was impressed by the clear and forceful arguments which were ably advanced on the Appellant's behalf by Mr. Williamson. I add a short judgment of my own addressed to what is plainly one of the critical issues in the case, namely the judge's rejection of the agreed expert evidence.
67. In my judgment, the judge was not assisted by the manner in which the expert evidence was prepared and presented. In particular, it does not seem to me that the experts' reports were sufficiently focused on what proved to be the critical issue in the case, namely that of pipe compatibility.
68. The order for directions made by the court on 28 April 2000 did not specify the issues which the experts were to address, save in the broadest of terms: "quantum and engineering". We do not have copies of the instructions given to the experts, and neither report in my judgment states "the substance of all material instructions, whether written or oral, on the basis of which the report was written" as required by CPR 35.10(3) and the relevant Practice Direction. Neither report, in my view, deals adequately with the question of incompatibility, and none of the 13 items on the agenda for the meeting of the two experts on 11 October 2000 addresses the point. It is against this background that the reference to "faulty control boxes" emerges as an "unlikely" cause of the leaks in the joint statement of the experts dated 6 November 2000.
69. Finally, it was most unfortunate that both experts gave their evidence before Mr. Colin Howard told the judge (amongst other things) that, due to the different types of pipes and couplings, he could sometimes "get a hacksaw blade between the pipe and the socket". Had the experts' opinion evidence been taken after the evidence of fact (as is the more appropriate course, in my judgment) both experts could have been cross-examined in a focused way on the application of the factual evidence to their opinions.
70. In these circumstances, the judge, in my judgment, was entitled to reject the expert evidence as to the causation of the leaks. He was able to do so because (1) he accepted the oral evidence of Colin and David Howard; (2) that evidence was corroborated by the letter written by Mr. David Howard on 25 January 1999 to which my Lord has referred; and (3) although the experts thought incompatibility "unlikely" as a cause, it was not so unlikely as to require the judge to reject it as an explanation, given the other evidence open to him.
71. The Civil Procedure Rules only require the instructions given to an expert to be disclosed where they are to a single joint expert under CPR 35.8. Although in any other case, the instructions to an expert are not privileged against disclosure, the court will not in relation to those instructions order disclosure of any specific document or permit any questioning in court, other than by the party who instructed the expert, unless it is satisfied that there are reasonable grounds to consider the statement of the instructions given in the expert's report to be inaccurate or incomplete.
72. In my judgment, there is much to be said for the practice in the Family Division of automatic disclosure of the instructions to an expert witness. This process focuses the minds of all involved on the relevant issues in the case, and enables inadequate or inaccurate instructions to be corrected before the expert reports.
73. The essence of expert evidence is that it should focus on the specific issues in the case. In my judgment, this did not happen here, with the result that the judge was obliged to do his best with the factual material. In these circumstances, I am satisfied that he reached a result which he was entitled to reach, and that apart from the "further claim", the appeal must be dismissed.

Lord Justice Schiemann:

74. I agree with both judgments.
Order: Appeal allowed in part; judgment reversed and substituted by a judgment in the sum of £8,149.02 including interest; claimant to recover the amount of costs he would have incurred both here and below had the claim been limited to £6.790 plus interest; claimant to pay remaining costs. (Order does not form part of the approved judgment)