England and Wales Court of Appeal (Civil Division) Decisions

IN THE COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE TECHNOLOGY AND CONSTRUCTION COURT
Edwards-Stuart J
HT 09 273

		Royal Courts of Justice Strand, London, WC2A 2LL
		24/01/2013

Lord Justice Toulson:

1. On Saturday 2 April 2005 a fire occurred at a recycling centre near Milton Keynes owned by the respondent ("the council"). The fire brigade was called and attended to it, but in the early hours of the following morning there was a fresh outbreak of fire at the premises. Proceedings were brought by the council against Mr Michael Nulty, a self employed electrical engineer who was working at the premises at the time of the first fire. He sadly died before the action came to trial.
2. At the time of the incident Mr Nulty was insured against professional liability by the National Insurance & Guarantee Corporation Limited ("NIG"), but it disclaimed any liability to indemnify him on the ground of failure to give prompt notification of the circumstances which gave rise to the claim, and it issued proceedings against Mr Nulty's estate and the council for a declaration that it had no liability under the policy.
3. The council's action and NIG's action were heard together by Edwards-Stuart J. The council limited its claim against the estate to £2 million, which was the limit of indemnity under the policy. NIG defended the council's claim, without prejudice to its denial of liability to provide indemnity under the policy.
4. Edwards-Stuart J handed down judgment on 3 November 2011 [2011] EWHC 2847 (TCC). It is an impressive judgment. The judge considered the facts in great detail and his analysis is closely reasoned. The judgment ran to 285 paragraphs. The judge found that the second fire resulted from a failure properly to extinguish the first fire and he found against NIG on the issue of coverage under the policy. There is no appeal against those findings. As to the cause of the fire, various possibilities were canvassed at the trial but the judge eliminated all but two possible candidates. Either it was caused by a cigarette end discarded by Mr Nulty or it was caused by arcing from a disused electric cable which had been left live and in a dangerous condition.
5. The judge concluded that neither cause, viewed on its own, seemed likely but that the arcing explanation was no more than a remote possibility and it was very much less likely than the discarded cigarette end explanation. He found that the council had discharged the burden of proving that Mr Nulty caused the fire and gave judgment for the council.
6. NIG appeals on the grounds that the judge erred in law in his approach to the question of causation, and that he erred in fact in overstating the improbability of the arcing theory and underestimating the improbability of the discarded cigarette end theory. Neither party suggested that if the court were to find that the judge erred in his approach to the law the case should be sent for a retrial. Both agreed that the court had the necessary material in those circumstances to reach its own decision on the facts and that this would be preferable to incurring the time and expense of a retrial.

The facts in outline

7. The processing area of the recycling centre contained two large baling machines. One was for commercial waste and the other was for domestic waste. There had been a third baler, known as the Boa baler after the manufacturer's name, but it had been removed in 1996 when a previous operator left the site. However, the electric cable that supplied it had been left in place and, worse still, at the time of the fire it was live, although that fact was not appreciated by anybody at the time. It had been left coiled beside the domestic baler, and insulating tape had been put over the uninsulated ends of the conductors.
8. Examination after the fire revealed that two of the coils had suffered arcing which had resulted in copper strands being severed. Less severe arcing had occurred at a third place, resulting in minor pitting to two strands. It was NIG's case that arcing of the Boa cable was the probable cause of the fire or at least was no less likely than a discarded cigarette end. The council's case was that arcing of the Boa cable was exceedingly unlikely to have been the cause of the fire, rather than a result of it, and that a discarded cigarette end was a far more likely explanation. Basing himself primarily on his evaluation of the expert witnesses, the judge preferred the council's case.
9. Each baler had a control panel located beside it. The electricity supply to the control panels came from a distribution board (DB 1) in a switch room, set into an office block, to which there was access from the processing area. The supply to DB 1 came from a main distribution board, which served the whole building and was in an area known as the plastics area or PLYSU. The PLYSU area was adjacent to the processing area but on the opposite side from the office block containing the switch room which housed DB 1. The judge attached to his judgment two plans showing the layout of the building, the balers, their control panels, the switch room and the PLYSU distribution board. The fire broke out in the area behind the domestic baler control panel.
10. Mr Nulty had often been called in by the council to do work at the premises and he was well familiar with them. At the time of the fire he had been an electrical engineer for nearly 30 years. At one stage in his life he had been trained as a fire fighter, and he had worked for a time on an irregular basis for the fire service when the demands of his business as an electrician allowed him to do so.
11. Two or three days before the fire, the domestic baler had developed an oil leak in the feed pipe to the hydraulic ram. An engineer was called in, but he did not arrive until the morning of the fire. At about 3am that day there was a power cut, which resulted in the centre having no electricity. The shift workers were sent home, because they could not carry on working in the dark, and for the same reason they did not clear up the debris on the processing floor as would usually have happened during the last part of the shift. So there was waste scattered all over the floor.
12. The operations manager, Mr Aylmer, was told about the power cut and he called in the electricity supply company. The engineer who had been called in to repair the oil leak on the domestic baler arrived and left before electricians came from the electricity company to restore power to the building. A forklift truck was brought up to the domestic baler and parked so that its headlights could be used to enable the engineer attending to the oil leak to see what he was doing. He repaired the leak and left the premises by about 11.00hrs.
13. Electricians from the local supply company arrived about 11.45hrs and left shortly after 13.00hrs after restoring power. They found that the cause of the power cut was a fault in the control panel of the commercial baler, which it was not their responsibility to repair.
14. Mr Nulty had been asked to attend the premises that day to deal with another matter, but on his arrival at about 12.30hrs he was asked to deal with the fault in the commercial baler control panel as a matter of urgency. Because it was more important for the commercial baler to be working than the domestic baler, he set about replacing the damaged parts on the commercial baler control panel with parts taken from the domestic baler control panel. The work took him the best part of 3 hours. From about 14.00hrs he was the only person working in the building.
15. Mr Nulty began by isolating the control panels for the two balers, using the control panel isolator switches, so that he could work on them safely. After completing the repairs to the commercial baler control panel he switched on the local isolator for that panel, but found that there was no electricity. He went to DB 1 and found that the circuit breaker, or MCCB, supplying the commercial baler had tripped. He switched it back on, but there was still no supply.
16. Mr Nulty then went to the main distribution board in the PLYSU area, where he found that the MCCB supplying DB 1 had tripped. He switched it on and returned to DB 1, where he switched on the MCCB for the commercial baler. This restored the supply. The supply to the domestic baler remained live, but it was isolated at its own control panel.
17. By then it was approaching 15.20hrs. The judge was able to make that finding because there were outdoor CCTV cameras which showed Mr Nulty at that time walking to the gate. There had been some problem with the gate and Mr Nulty had been asked to help the security guard to fix it. At 15.37hrs he was seen walking away from the gate. Shortly before 15.42hrs he was seen walking towards the canteen. At 15.55hrs the fire alarm was activated. Mr Nulty heard it from the canteen and immediately went to the scene. As he entered the building he saw fire around the rear of the domestic baler. He used his mobile phone to call the fire brigade and set about himself trying to extinguish the fire by use of a nearby hose reel.
18. Mr Nulty told investigators, and confirmed in his witness statement, that he had gone to the staff canteen portacabin to have a cup and tea and a cigarette. He was well aware that smoking was prohibited inside the processing area. He said in a witness statement provided to NIG's solicitors:

"9. I am adamant that I did not smoke anywhere other than in the designated smoking area on 2 April 2005.

10. I would never have taken the risk of smoking inside the processing area. It was full of paper and machinery. You'd have to be pretty reckless to do that. The risk of fire was obvious. I would never have taken such a risk.

11. I also really needed to maintain good commercial relations with people at the Recycling Centre. It was an important source of work for me back then. I wouldn't have wanted to do anything which would have put them off wanting to hire me again.

…

13. I recall that on the day of the fire the Recycling Centre and the processing area were really untidy. There were paper and cans lying around everywhere, all over the floor. In some places the waste was piled up really high. It was a real mess, which I suppose must have been normal for those types of places."

The judge's approach

19. At the beginning of his judgment Edwards-Stuart J said that it was common ground that there were only three candidates for the cause of the first fire:

"First, a cigarette end carelessly discarded by someone smoking in the area where the fire started. Second, arcing from a live electric cable. Third, arson by an intruder. As I have said, the council alleges that the fire was caused by the first of these, and that it was Mr Nulty who was to blame. NIG contends that if the fire was caused by a carelessly discarded cigarette, then it could equally well have been discarded by someone else. But its primary case is that the fire was caused by electrical arcing or, alternatively, by an intruder."

20. The judge rejected the possibilities that the fire was caused by an intruder or by a cigarette discarded by someone other than Mr Nulty. There is no appeal against those conclusions.
21. The judge examined the possibility that the fire was caused by arcing of the Boa cable in considerable detail at [137] to [203]. He set out his findings at [204] and summarised his conclusion at [205]:

"For all these reasons I consider it very unlikely that arcing of the small Boa cable caused the first fire. There is a remote possibility that it did, but I regard the likelihood that this happened as no higher than that. "

22. It will be necessary in due course to consider the soundness of that conclusion.
23. The judge then considered the possibility that the fire was caused by Mr Nulty carelessly discarding a cigarette end. He considered that it was a feasible scenario, and he referred to two aspects of Mr Nulty's conduct during the investigation of the fire which he described as pointers consistent with the conclusion that Mr Nulty caused the fire.
24. Having considered the rival suggested causes, the judge concluded at [215]:

"Accordingly, of the three suggested causes of the fire, none of which, if taken on its own, is one that is inherently likely, I find that a cigarette end carelessly discarded by Mr Nulty is the most probable. In the light of this conclusion I must now turn to the authorities in order to decide whether or not that finding is sufficient for me to hold as a result that the council has in law discharged the burden of proving that Mr Nulty caused the first fire."

25. The judge then turned to consider the authorities, beginning with Lord Brandon's judgment in The Popi M [1985] 1 WLR 948. Among the subsequent authorities, he highlighted in particular the following passage from the judgment of Waller LJ in Kiani v Land Rover Limited [2006] EWCA Civ 880 at [30], which he set out in bold type:

"I do not myself think that it is false logic to reason that where only two possibilities are under consideration both of which seem unlikely, if one seems much less likely than the other, the less likely can be discounted thus making the first likely to have happened on the balance of probabilities."

26. The judge set out his final conclusion at [219]:

"In my judgment there are only three possible candidates for the cause of the first fire and they are the ones that I have mentioned. I accept that it might be regarded as unlikely that an experienced electrical engineer, who had in past been a part time fireman, would choose to smoke in a building to which he knew a no-smoking policy applied and then discard the cigarette end – albeit one that he thought he had stubbed out – into flammable waste lying on the floor. But if the only other possible causes of this fire are very much less likely, as I find they are, then in law the discarded cigarette becomes the probable cause of the first fire. As Waller LJ observed in the passage that I have emphasised above, this process of reasoning is not false logic."

27. He added by way of "afterword" at [283] and [284]:

"I have found this an anxious and difficult case. To make a finding against a person who has been unable to come to court and defend himself is not something any court would wish to do lightly. It is for that reason that I have explored in detail, and perhaps some may think in excessive detail, the possible alternative causes of this fire and, in particular, the likelihood of arcing from the small Boa baler cable.

Whilst I have found that Mr Nulty's negligence caused the first fire, I doubt very much if he thought that he was doing anything that created a serious risk. But, on my findings, on this one occasion he was mistaken…However, in all other respects Mr Nulty appears to have been a competent and careful engineer who had provided valuable services to the centre."

28. Mr Eklund QC submitted that the judge's statement of law at [219] ("if the only other possible causes of the fire are very much less likely,…then in law the discarded cigarette becomes the probable cause of the first fire") is contrary to The Popi M. Mr Rigney QC submitted that the judge's statement of the law is consistent with The Popi M, when properly understood, and consistent with later Court of Appeal authority including particularly Kiani v Land Rover Limited. Mr Rigney also submitted that it was wrong to read paragraph [219] of the judgment in isolation from the preceding paragraphs and that even if, taken in isolation, it was open to criticism, no valid criticism could be made when the judgment is read in full.
29. We were referred to the judgments of Bingham J, [1983] 2 Lloyd's Rep 235, and Lord Brandon in The Popi M and to a number of later authorities in which the case has been discussed in different contexts. Without meaning any disrespect either to counsel or to the courts whose judgments have been cited, I do not intend to go through them all because I do not consider it necessary and I am conscious that excessive citation can lead to excessive complication, resulting in less rather than more enlightenment.
30. The Popi M sank in calm seas and fair weather as a result of a large and sudden entry of water into her engine room through her shell plating. The vessel's owners claimed against her hull and machinery underwriters, contending that the loss was caused by a peril of the sea or alternatively by crew negligence. The suggested peril of the sea was a moving submerged object, i.e. a submarine. The underwriters contended that the vessel was not seaworthy. More specifically, the underwriters advanced a mechanism for unseaworthiness through wear and tear, based on expert metallurgical evidence. The judge rejected that theory. He also rejected the owners' argument that there had been crew negligence. That left the possibilities that the vessel was in some other way unseaworthy or that it collided with a submarine. At a high level of generality, neither of those explanations would necessarily be hard to imagine. It is far from unknown for vessels to be sent to sea in an unseaworthy state and it is far from unknown for vessels to collide with submersible objects. However, the evidence to support either theory on the particular facts of the case was unsatisfactory, as the experts on both sides candidly recognised. Bingham J observed that on each side there was recognition that the hypothesis for which that side contended was highly improbable; it was supported as the most likely hypothesis only because any other hypothesis, and in particular the hypothesis advanced by the other party, was regarded as almost (if not altogether) impossible. He commented at 245:

"Rarely can competing menus have been proffered with such guarded recommendations by each of the chefs responsible."

31. After setting out cogent reasons why the submarine theory was improbable and his reasons for rejecting the metallurgical argument advanced by the underwriters, Bingham J stated the position in which he found himself and his conclusion at 248:

"In the result, I find myself driven to conclude that the defendants' wear and tear explanation must on the evidence be effectively ruled out. That leaves me with a choice between the owners' submarine hypothesis and the possibility that the casualty occurred as a result of wear and tear but by a mechanism which remains in doubt. Cases must be decided on evidence. My conclusion is that despite its inherent improbability, and despite the disbelief with which I have throughout been inclined to regard it, the owners' submarine hypothesis must be accepted as, on the balance of probabilities, the explanation of this casualty."

32. In the House of Lords Lord Brandon began by saying, at 951, that the appeal did not raise any question of law except possibly the question what is meant by proof "on a balance of probabilities". In a celebrated passage at 955 he likened Bingham J's approach to that of Sherlock Holmes:

"My lords, the late Sir Arthur Conan Doyle in his book The Sign of Four, describes his hero, Mr Sherlock Holmes, as saying to the latter's friend, Dr Watson: "How often have I said to you that, when you have eliminated the impossible, whatever remains, however improbable must be the truth?" It is, no doubt, on the basis of this well-known but unjudicial dictum that Bingham J decided to accept the ship owners' submarine theory, even though he regarded it, for seven cogent reasons, as extremely improbable.

In my view there are three reasons why it is inappropriate to apply the dictum of Mr Sherlock Holmes, to which I have just referred, to the process of fact-finding which a judge of first instance has to perform at the conclusion of a case of the kind here concerned.

The first reason is one which I have already sought to emphasise as being of great importance, namely that the judge is not always bound to make a finding one way or the other with regard to the facts averred by the parties. He has open to him the third alternative of saying that the party on whom the burden of proof lies in relation to any averment made by him has failed to discharge that burden. No judge likes to decide cases on the burden of proof if he can legitimately avoid having to do so. There are cases, however, in which, owing to the unsatisfactory state of the evidence or otherwise, deciding on the burden of proof is the only just course for him to take.

The second reason is that the dictum can only apply when all relevant facts are known, so that all possible explanations, except a single extremely improbable one, can properly be eliminated. That state of affairs does not exist in the present case: to take but one example, the ship sank in such deep water that a diver's examination of the nature of the aperture, which might well have thrown light on its cause, could not be carried out.

The third reason is that the legal concept of proof of a case on a balance of probabilities must be applied with common sense. It requires a judge of first instance, before he finds that a particular event occurred, to be satisfied on the evidence that it is more likely to have occurred than not. If a judge concludes, on a whole series of cogent grounds, that the occurrence of an event is extremely improbable, a finding by him that it is nevertheless more likely to have occurred than not, does not accord with common sense. "

33. Lord Brandon concluded, at 957, that the judge ought to have found simply that the ship owners' case was not proved.
34. A case based on circumstantial evidence depends for its cogency on the combination of relevant circumstances and the likelihood or unlikelihood of coincidence. A party advancing it argues that the circumstances can only or most probably be accounted for by the explanation which it suggests. Consideration of such a case necessarily involves looking at the whole picture, including what gaps there are in the evidence, whether the individual factors relied upon are in themselves properly established, what factors may point away from the suggested explanation and what other explanation might fit the circumstances. As Lord Mance observed in Datec Electronics Holdings Limited v UPS limited [2007] UKHL 23, [2007] 1 WLR 1325, at 48 and 50, there is an inherent risk that a systematic consideration of the possibilities could become a process of elimination "leading to no more than a conclusion regarding the least unlikely cause of loss", which was the fault identified in The Popi M. So at the end of any such systematic analysis, the court has to stand back and ask itself the ultimate question whether it is satisfied that the suggested explanation is more likely than not to be true. The elimination of other possibilities as more implausible may well lead to that conclusion, but that will be a conclusion of fact: there is no rule of law that it must do so. I do not read any of the statements in any of the other authorities to which we were referred as intending to suggest otherwise.
35. The civil "balance of probability" test means no less and no more than that the court must be satisfied on rational and objective grounds that the case for believing that the suggested means of causation occurred is stronger than the case for not so believing. In the USA the usual formulation of this standard is a "preponderance of the evidence". In the British Commonwealth the generally favoured term is a "balance of probability". They mean the same. Sometimes the "balance of probability" standard is expressed mathematically as "50 + % probability", but this can carry with it a danger of pseudo-mathematics, as the argument in this case demonstrated. When judging whether a case for believing that an event was caused in a particular way is stronger that the case for not so believing, the process is not scientific (although it may obviously include evaluation of scientific evidence) and to express the probability of some event having happened in percentage terms is illusory.
36. Mr Rigney submitted that balance of probability means a probability greater than 50%. If there is a closed list of possibilities, and if one possibility is more likely than the other, by definition that has a greater probability than 50%. If there is a closed list of more than two possibilities, the court should ascribe a probability factor to them individually in order to determine whether one had a probability figure greater than 50%.
37. I would reject that approach. It is not only over-formulaic but it is intrinsically unsound. The chances of something happening in the future may be expressed in terms of percentage. Epidemiological evidence may enable doctors to say that on average smokers increase their risk of lung cancer by X%. But you cannot properly say that there is a 25 per cent chance that something has happened: Hotson v East Berkshire Health Authority [1987] AC 750. Either it has or it has not. In deciding a question of past fact the court will, of course, give the answer which it believes is more likely to be (more probably) the right answer than the wrong answer, but it arrives at its conclusion by considering on an overall assessment of the evidence (i.e. on a preponderance of the evidence) whether the case for believing that the suggested event happened is more compelling than the case for not reaching that belief (which is not necessarily the same as believing positively that it did not happen).
38. Mr Rigney's submissions were made in support of the judge's statement at [219] that if the only possible causes of the fire other than a discarded cigarette are very much less likely, "in law the discarded cigarette becomes the probable cause".
39. In expressing himself in those terms, the judge went further than he needed in order to answer the question which he had raised at [215]. Having concluded that a cigarette end carelessly discarded by Mr Nulty was the most probable cause of the fire, he posed the question whether on the authorities that finding was "sufficient" for him to hold that the council had discharged the burden of proof.
40. The answer to that question was yes, provided (as I think is implicit in his reasoning) that he was satisfied on all the evidence that the case for believing that Mr Nulty caused the fire was stronger than the case for not coming to that belief. The proviso is important as illustrated and explained in the Popi M. In that case the combined effect of the gaps in the court's knowledge and the cogency of the factors telling against the theory of a collision with a submarine was that the court could not properly be persuaded that the case for believing the submarine theory was stronger than the case for remaining agnostic.
41. Mr Eklund placed great reliance on the judge's characterisation at [215] of the three suggested causes of the fire as ones "none of which, if taken on its own, is one that is inherently likely". He submitted that this meant that the judge considered the discarded cigarette theory to be inherently improbable and therefore he ought to have found that the council's claim failed. In my view that is a misreading of the judgment when read as a whole. Earlier in his judgment the judge had considered the scenario advanced by the council and found it to be objectively plausible. However, he recognised that Mr Nulty would not have been expected to have a propensity to act in that way, for the reasons which he gave, and for that reason the scenario did not seem likely "if taken on its own". He would not have concluded that Mr Nulty had acted in a way which would have seemed out of character if there had been any other plausible explanation, but he was satisfied that there was none. This reading is to my mind reinforced by the judge's comments in his afterword.
42. If, in answer to the question which the judge posed at [215] about whether his findings with regard to the rival scenarios were sufficient for him to hold in favour of the council, the judge had said that such holding was open to him on the authorities, there would have been no error of law on the facts as he found them. However, he went further at [219] by stating it as a proposition of law that if the only other possible causes of the fire were very much less likely, the discarded cigarette became in law the probable cause of the fire. For the reasons which I have given, I consider that in that respect he erred. There is no such rule of law. However, as I have stressed, it does not follow that the judge's conclusion was wrong on the facts as he found them. At this stage it is necessary to look more closely at the judge's findings about the rival theories in the light of the attack made on them by NIG.

Expert evidence

43. Each side called a fire expert and an electrical expert. They were respectively Mrs Jo Lawson and Mr David Bailey for the council and Mr Clifford Christie and Dr Richard Lipczynski for NIG. Mrs Lawson's investigation of the fire began on 5 April 2005. Unfortunately it was not until 7 April 2005, when Mr Bailey first visited the premises, that it was appreciated that the Boa cable had been live at the time of the fire. In the meantime the cable had been moved in the course of the investigations. Photographs taken by Mrs Lawson on 5 April showed its position at the time of the fire but it was not closely examined at that stage. Generally, however, the judge found Mrs Lawson to be a good witness and good expert. There were no scientific differences between her and Mr Christie. Their differences lay in their ultimate assessment of the relative probabilities. Mr Christie's position was simply that he did not feel able as an expert to choose between the possible causes of the fire and he regarded that as a matter for the court to determine in the light of all the evidence. The significant technical differences were between the electrical experts and the judge examined their rival theories in close detail. He found Mr Bailey to be a competent expert and straightforward witness. Where his opinions differed from those of Dr Lipczynski, the judge generally preferred the views of Mr Bailey, mainly because he found them to be based on scientific reasoning rather than assertion. The judge did not find Dr Lipczynski to be an expert on whose evidence he could rely and he gave a number of examples of Dr Lipczynski's deficiencies. In those circumstances Mr Eklund does not seek to rely on Dr Lipczynski in support of the appeal.

Boa cable theory

44. The cable was a four core armoured cable. It was originally connected to the Boa baler which had been installed in or about March 1996 by a company that operated the recycling centre for a period of about 6 months. At the end of that period the company removed the Boa baler but left behind the cable. It was later coiled up and left beside the domestic baler. It was looped over the steel frame which supported the baler, with part of the coil lying against the side of the upright framework and part of it, including the cable end, lying on the floor.
45. Over the final 60cm of the cable, the outer armoured sheaf had been stripped off to expose the four cores. Each core was insulated with a layer of cross-linked polyethylene or XLPE. This is a hard plastic material, much thicker and tougher than the standard insulation found on ordinary cable used by electricians in domestic installations. The judge said at [139]:

"I have been provided with a sample of both types of cable and XLPE is noticeably harder than the PVC insulation. One would have to hit it with a hard, heavy and sharp implement to make any impression on it."

46. The final 1.5cm of each core was stripped of insulation in order to permit connection with the Boa baler. The bare ends were in some way insulated and, as far as anyone could tell, that temporary insulation maintained its integrity until the time of the fire. Dangerously, the other end of the cable was left connected to the MCCB in DB 1.
47. The points at which severe arcing was found to have occurred on two of the four cables were about 18.5cm apart when the cores were laid side by side. The point at which minor pitting had occurred was between the two areas of severe arcing, approximately 13.5cm away from one and 5cm away from the other. The cable could not have been coiled in such a way as to bring the areas of arcing damage into alignment. Accordingly, if the arcing events were not caused by the fire but resulted from some other form of physical damage to the cable, they must have been separately caused.
48. Dr Lipczynski's evidence was that each incident of severe arcing must have resulted in a fault current which would have caused the MCCB to trip in less than 20 milliseconds. If he was right, it followed that the arcing damage could not be entirely attributed to the fire, since the second severe arcing could not have occurred after the cable had ceased to be live. NIG argued that if an arcing event of such severity had occurred on some occasion prior to the fire, after which the MCCB had been switched back on, a repetition would be a likely explanation of the fire.
49. However, Mr Bailey gave cogent evidence which refuted Dr Lipczynski's evidence that arcing of such severity must instantly have caused the MCCB to trip. The judge accepted Mr Bailey's evidence that all the arcing damage was capable of having been caused by the fire. It was also scientifically possible for some of the arcing damage to have occurred before the fire and for a later arcing incident to have caused the fire.
50. The judge examined the possibility of at least one instance of arcing having occurred prior to the fire. He concluded that it was most improbable. For one thing, it was most unlikely that an event would have occurred to cause such arcing without someone realising it. It was also most unlikely that if the small Boa cable MCCB had tripped prior to the fire, the MCCB would have been reset without any inquiry.
51. There remained for consideration the possibility that the fire was caused by an arcing event without any arcing event having occurred prior to the fire. This would require the combination of damage causing exposure of bare wire, contact between the wire and earthed metalwork, and the supply of power. The judge considered each of these matters.
52. There was a metal cable tray that ran at about ground level from the control panel to the domestic baler, on part of which the cable was resting. If one of the cores of the cable had been lying across the vertical side of the cable tray, it could in theory have been damaged by some heavy object falling on it at the point where it crossed the edge of the cable tray, but if this had happened it is probable that somebody would have been aware of it. The judge considered the possibility that such damage might have been caused by the operator of the forklift truck which was used to light the scene while the oil leak was repaired on the morning of the fire, but there would have been no cause for him to bring the forklift truck so close to the domestic baler as to create a risk of contact between the forks and the cable. The judge considered that this theory could be excluded.
53. Two other candidates for causing exposure of the wire were suggested: damage through contamination by chemicals, in particular hydraulic oil, and damage by rodent activity. Dr Lipczynski advanced the former, but without any evidence to support it, and Mr Bailey was not cross examined on his evidence that XLPE insulation would be very unlikely to be degraded by any chemicals which one would normally expect to find at a waste recycling centre. The judge rejected that possibility and it did not feature on the appeal.
54. The possibility of rodent damage had not been raised as anything other than a background risk prior to the trial. It first arose as a significant possibility during the course of the trial and therefore the council's experts had not done any research into the possibility of rats gnawing through XLPE. It arose during the course of the trial in the cross examination of Mr Aylmer. He was asked about the type of instance which might cause the breakdown of a baler and he said that sometimes a rat might gnaw through a wire, but he was not more specific.
55. The judge described this, at [192], as an unexpected boost for NIG's case. He observed that unfortunately there was no evidence before the court as to whether rats would gnaw through insulation made of XLPE as distinct from the PVC insulation typically used on smaller cables.
56. The judge concluded that a sequence of events by which (1) rodent damage occurred to one of the cores, (2) during the period of the power cut the exposed section was somehow brought into contact with earthed metalwork, (3) arcing occurred when power was restored to the cable and (4) a spark landed on flammable material, causing the fire, could not be excluded altogether but was highly improbable.
57. Mr Eklund criticised the judge's reasoning in a number of respects. He has a difficult task to persuade an appellate court to interfere with the judge's primary conclusions on a complex factual matter of this kind, bearing in mind that the judge had the benefit of receiving first hand the evidence of the experts to which he gave the most careful consideration. It is not enough to show that some particular comment or statement in a lengthy and detailed analysis may be open to dispute. The appellant has to show that there is serious ground for doubting the judge's overall conclusion. In my opinion NIG has fallen far short of doing so. The judge was entitled to find, as he did, that the Boa cable was not in a position where it appeared to be obstructing anything, nor was it in any form of thoroughfare. There was no apparent reason why anybody should have wished to move it. Although it had been potentially dangerous to leave the cable where it was, the evidence suggested that it had remained in that condition for many years without causing harm.
58. The judge was entitled to discount the possibility of the cable being damaged by some heavy blow. That left the rat theory for consideration. That scenario would have required the following:

1. a rat gnawing through a section of the XLPE;

2. somebody moving the cable so as to bring that section of the core into contact with the metalwork of the cable tray while power was off;

3. the occurrence of an arcing event on the restoration of power to the cable which initiated a smouldering fire;

4. the cable remaining live for over half an hour, so as to permit the other areas of arcing damage to occur after the smouldering fire had turned into a flaming fire.

59. On the supposition that a rat could have gnawed through the XPLE (for which there was no direct evidence), there was a period during the power cut when theoretically the damaged section of cable could have been brought into contact with the metal tray. However, the only people who worked in that vicinity during the power cut were Mr Nulty and the engineer who repaired the oil leak. Mr Nulty never suggested that he moved the cable or that he might have done so inadvertently. As to the engineer, there are photographs in the bundle which show the oil feed pipe to the hydraulic ramp (and the flange which had been leaking) in relation to the position of the Boa cable. The engineer would have had no cause to come into contact with the cable and it is hard to suppose that he would have done so accidentally.
60. The restoration of power to the cable occurred shortly before 15.20hrs. The fire alarm was activated at 15.55hrs. Although Mr Bailey disagreed with Dr Lipczynski's evidence that a severe arcing event would necessarily have led to immediate tripping of the Boa baler MCCB, he considered it improbable that the MCCB would have remained on long enough to permit an initially smouldering fire to develop into a flaming fire capable of causing the further arcing damage. In summary, Mr Bailey considered that the suggested scenario relied on "a whole series of low probability events occurring" and that, taking everything into consideration, it was "a very unlikely explanation for the fire". The judge was entitled to conclude that it was indeed no more than "a remote possibility".

Discarded cigarette end theory

61. Mr Eklund criticised the judge for constructing a detailed possible scenario of how, when and where Mr Nulty smoked a cigarette and discarded the end, which he then proceeded to treat as a factual account when it was no more than speculation. In examining the rival explanations for the fire, it was necessary for the judge to imagine what each entailed. In the passage about which complaint is made, the judge was considering the plausibility of the discarded cigarette explanation. It would have been sufficient for him to say that there was nothing physically or scientifically implausible about the cigarette end explanation, and that the risk of Mr Nulty being detected would have been negligible since he was alone in the building. There could have been no criticism of such a conclusion, and that was essentially what the judge found.
62. Mr Eklund also criticised the judge for taking into account two other matters as pointers consistent with the conclusion that Mr Nulty caused the fire. One was what the judge described as "his curious reaction" when asked during a police interview about providing a sample of DNA. The other was a note written by Mr Nulty in November 2006 in which he suggested that he had told investigators about the Boa cable.
63. As to the first point, Mr Nulty was interviewed under caution by the police on 3 February 2006 in relation to the fires. He was asked if he had any view as to how the first fire started and he replied:

"The only thing I can think of what started it – at the back of the baler, there's a roll of cable there and that cable has been there, I didn't know at the time, but that's been there a long time and the ends were exposed. The other end of the cable was connected to the switchboard."

64. Earlier in the interview he was told that a cigarette end had been found near the area in which he had been working, and at the end of the interview he was asked if he was willing to provide a sample of his DNA. Mr Nulty said:

"You've got to realise, I push all that out of the way. So if there's a cigarette end there or cardboard there, I could have touched that anyhow."

65. There may have been rubbish on the floor around the control boxes where Mr Nulty was working, but the council's point was that it is hard to imagine him picking up an individual cigarette end with his bare hands. The judge was entitled to regard his response as a curious reaction and as a factor consistent with him having in fact smoked a cigarette on the premises.
66. As to the second point, in the note dated 6 November 2006 Mr Nulty said:

"The afternoon following the fire, on inspecting the site with an investigator I noticed a large roll of cable with bare ends at the rear of the boiler. The other end was connected to the board, the breaker of which had tripped. I pointed this out to the investigator, she took a photo of the board."

67. Mrs Lawson gave evidence that nothing was said by Mr Nulty about the Boa cable when she was on site between 5 and 8 April 2005, but that after her initial investigations she spoke to him and asked him, as an electrician familiar with the site, to identify what the cable was. He said that he did not know and she asked him to find out. On 22 April 2005 he told her that he had been back to the site and had traced the cable. He confirmed that it was the small Boa cable and that it was still connected to the MCCB. The judge considered the note dated 6 November 2006 to be a pointer consistent with Mr Nulty having caused the fire because the note was incorrect and it suggested "that he was concerned to try and cast doubt on the conclusions of the fire investigators".
68. I would not myself draw any adverse conclusion from the note. The judge was entitled on the evidence of Mrs Lawson to find that the note was incorrect, and Mr Nulty was undoubtedly trying to suggest that the Boa cable was the cause of the fire. But he had made that suggestion already to the police, so he was not changing his ground. The fact that he was suggesting that the Boa cable was the cause of the fire is equally consistent with guilt or innocence. By the time that the note dated 6 November 2006 was written, the fact that Boa cable had been attached at the time of the fire was well established. The note may show that he was unreliable about the history of its discovery, but I do not see that it takes matters further. However, this was not a major part of the judge's reasoning and I do not see that it affects his overall conclusions.

Conclusion

69. The judge's finding that the cause of the fire was "very much less likely" to have been arcing of the Boa cable than the cigarette end discarded by Mr Nulty was reached after a painstaking examination of the evidence and was properly open to him. Rational analysis of the Boa cable theory showed that it was highly improbable. It would have required a remarkable combination of unlikely events. The objection to the discarded cigarette end theory was of a different nature. There was no comparable scientific or practical improbability about it. Mr Nulty was working alone at the relevant place and time. He had the opportunity and could well have had the temptation to do what the council alleged. The objection to it was that he would not have been expected to behave in such a way, but the circumstantial evidence that he did so on this occasion was compelling. In my view the judge was right to find that he did so and I would dismiss the appeal.

Lord Justice Beatson:

70. I agree.

Lord Justice Longmore:

71. I also agree.