Neutral Citation Number: [2008] EWCA Civ 907
Case No: B3/2008/1142
IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION
MR JUSTICE DAVID STEEL
LOWER COURT NO: TLQ/07/1192 
Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 31/07/2008
Before:

LORD PHILLIPS OF WORTH MATRAVERS, LORD CHIEF JUSTICE OF ENGLAND AND WALES
LORD JUSTICE MAY
and
LORD JUSTICE WILSON
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Between :

	TIMOTHY PERRY AND CATHERINE PERRY	Appellants	
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	SAMUEL DAVID HARRIS (a minor and a patient, suing by his Mother and Litigation friend, Janet Harris)	Respondent	
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(Transcript of the Handed Down Judgment of
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Mr Graham Eklund QC (instructed by Keoghs LLP, Bolton) appeared for the Appellants.
Miss Susan Rodway QC (instructed by Julie Reynolds, Tunbridge Wells) appeared for the Respondent.

Hearing date: 8 July 2008
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Judgment

LORD PHILLIPS OF WORTH MATRAVERS, CJ : 
1.	This is the judgment of the court, prepared with particular assistance from Wilson LJ.
INTRODUCTION
2.	On 8 May 2008, in the High Court, Queen’s Bench Division, Mr Justice David Steel gave judgment for Samuel Harris, the claimant, against Mr Timothy Perry and Mrs Catherine Perry, the defendants.  By a written, reserved judgment, he held that they were liable to the claimant in negligence and adjourned the assessment of his damages.  With the judge’s permission, the defendants appeal to this court against his conclusion that they were liable to the claimant.
3.	Before the judge there was a further party to the proceedings, namely the claimant’s father, Mr David Harris.  He was joined both by the defendants as a third party and by the claimant as a third defendant.  The judge dismissed both claims against him and, in that neither the defendants nor the claimant appeal against the dismissal, the claimant’s father is not a party to this appeal.
4.	On 10 September 2005 the claimant, who was born on 23 June 1994 and so was then aged 11 years and three months, was seriously injured whilst playing on a bouncy castle.  He had just performed a somersault on it when, before he had time to get to his feet, another, much taller and older boy also performed a somersault on it and, while the latter’s body was rotating, his heel accidentally struck the claimant’s forehead.  The claimant suffered a depressed skull fracture and a subdural haematoma in the left frontal-parietal lobe.  It seems that the injury will have severe, permanent cognitive, behavioural, emotional and social consequences for him.  It is impossible not to be deeply moved by the plight of the claimant, of his mother (divorced from his father) who struggles to care for him, and of his sister. 
5.	The defendants had hired both the castle and a second inflatable for a birthday party for their triplets, who had their tenth birthdays on that day.  The claimant was not invited to the party, which had not begun at the time (about 12:15pm) when he was injured.  We will explain how he came to be on the castle.  The second inflatable was a bungee run.  It had two lanes, thus for use by up to two persons at the same time, in particular in competition.  It worked in the following way. A belt was strapped around the person; attached to the belt was a cord, the other end of which was attached to the back of the run; the person ran forward as far and as fast as possible; before he arrived at the front of the run, a mechanism was triggered by which the cord was retracted; he slapped a marker down on the centre wall in order to prove how far he had got; and he was catapulted back down the inflated sides of his lane until he bounced against the inflated back of the run.
6.	The defendants hired the two inflatables for the day.  Although they intended them for use by the children, they chose a size suitable in both cases for adults as well as children.  The dimensions of the run are irrelevant; but those of the castle were 13'9" wide, i.e. between the inside of the inflated side-walls, and 13'4" long, i.e. from the inside of the inflated back wall to the open front.  Outside the defendants’ back garden was a long field which was open to the public and which was primarily used for football by the school which the triplets attended.  The defendants obtained the permission of the school to pitch the inflatables on the field that day, which was a Saturday.  They caused the hire company to pitch them not far from their back garden gate.  The company pitched them at about 8:30am and inflated them with a generator, which they left on site.  The defendants deliberately caused them to be pitched so that they faced not in precisely the same direction but to some extent inwards towards each other, namely at an angle of about 70°.  In that way – so the defendants reasoned – one or other of them could stand back and more easily watch children on both of them at the same time.
7.	In the morning prior to the party, various children were, as we will explain, playing on the inflatables.  Mrs Perry was supervising them from a position in front of both inflatables.  Mr Perry played no role in the ensuing events.  So when, from now onwards, we make reference to “the defendant”, it will be a reference to Mrs Perry.
8.	The major dispute of fact before the judge was whether the defendant had given express permission to the claimant and indeed to his friend, Simon Spicer (“Simon”), who was four months older than him, to play on the castle.  Simon, who gave evidence on behalf of the claimant, said that he and the claimant had asked her for such permission and that she had given it.  The evidence of the defendant, by contrast, was that she had specifically told the claimant not to play on the castle.  In this she was supported by the evidence of the much taller, older boy to whom we have referred, namely Sam Pring (“Sam”).  The judge – unsurprisingly in the light of the facts which we will relate – found that the defendant had indeed given express permission to the claimant and Simon to play on the castle.  There is no appeal against this finding.
9.	It was agreed before the judge that any such finding would have important consequences.  For it was conceded by Mr Eklund QC on her behalf that, if she had given them permission, the defendant owed each of the two boys a duty of care.
10.	In a nutshell the accident to the claimant occurred when the defendant’s back was turned from the castle.  She had gone to the run to help a child to strap the belt around himself.  While she was attending to him, children began to do somersaults on the castle. Specifically three children each did one somersault – first Simon, then the claimant and then Sam, whose somersault accidentally caused the injuries to the claimant.
11.	The judge held, primarily, that the defendant’s duty of care to the claimant required her to maintain “uninterrupted supervision” of the castle, which he otherwise described as a “permanent look-out” and a “continuous watch”.  He then proceeded to consider whether, had the defendant so acted, she would have been able to stop the somersaults in time to prevent the accident; and he held that she would have been able to do so and thus that her breach caused the accident.  The primary submission of Mr Eklund in support of the appeal is that, in holding that the defendant’s duty of care was to maintain a continuous watch on the castle, the judge interpreted her duty too strictly and that his process of reasoning in that regard was flawed.  Mr Eklund’s further submission in this area is that the judge was wrong to conclude that, even had she been maintaining a continuous watch, she could have stopped the sudden somersaulting in time to prevent the accident.
12.	The judge held, secondarily, that the defendant’s duty of care to the claimant obliged her not to allow Sam to use the castle at the same time as the other, smaller, children were using it. Mr Eklund submits that, in this regard also, the judge interpreted the defendant’s duty too strictly and, in particular, without weighing what the defendant knew or believed about Sam’s temperament and level of responsibility.
THE FACTS IN DETAIL
13.	The judge recorded the facts with characteristic economy; indeed, according to Mr Eklund, with excessive economy. We will record them more fully and will take care not to recite as fact, evidence which was disputed and was not the subject of a finding by the judge.
14.	It was the practice of the claimant’s father, who managed a boys’ football team, to conduct training sessions with them on the field between 10:00am and noon on Saturday mornings.  The claimant was a member of the team. On 10 September 2005 the claimant’s father collected him from his home and they arrived at the field shortly prior to 10:00am.  Another member of the team was Beau Clayton (“Beau”), whose mother, Mrs Clayton, did administrative work for the team and assisted the claimant’s father at the sessions on Saturday mornings. Mrs Clayton duly arrived with Beau, who was also aged about 11, and with her daughter Liberty, who was aged about 9 or 10 and who did not participate in the session.  About 13 other boys, all aged about 11, arrived for the session.  They included the claimant’s friend, Simon, who was aged almost 12, and Beau’s friend, Luke Betterson (“Luke”).
15.	When he arrived, the claimant’s father noticed the inflatables.  He also noticed a tall boy, whom he did not know, standing near them.  This was Sam.  He was then aged just 15 and was, even then, extremely tall for his age, perhaps about 5'9".  The height of the claimant, by contrast, was then about 4' 8".  Sam lived next door to the defendants.  They had known him for about three years.  Although he was much older, he had become quite friendly with the triplets, who consisted of one boy, James, and two girls.  Sometimes Sam kicked a ball around in the field with James and, perhaps, the girls; sometimes he came into their house and played games with them inside.  The defendant’s evidence was that Sam always struck her as responsible; and the judge quoted with approval her description of him as a “gentle giant”.  Mr Eklund submits that the adjective is as significant as the noun.
16.	The training session began.  Liberty watched it with Mrs Clayton. At about 10:30am the defendant walked over to them and asked whether Liberty would like to come and play on the castle.  Liberty accepted the invitation, went over to the castle and began to play on it.  By then other children had also begun to play on it, namely Sam, James, and either one or both of the defendant’s daughters.  It is not suggested that any of them was wearing shoes at any stage while on the castle.  The defendant watched them, primarily from a position about 17' in front of both inflatables.
17.	Broadly that situation continued until noon.  Of course the children did not bounce continuously.  From time to time they got off the castle and then on again.  Some tried the run. Indeed at one point the castle was deflated and then re-inflated.  From where she was standing, near the footballers, Mrs Clayton could see Liberty on the castle.  Twice Mrs Clayton went over to the castle, chatted to the defendant for several minutes, no doubt watched Liberty more closely, and returned to the training session.  In evidence she accepted that she would not have allowed Liberty to continue to play on the castle if she had considered that the defendant was not providing proper supervision.  But Mrs Clayton added what Miss Rodway Q.C. for the claimant submits is an important rider, namely that she assumed, in the light of his height and apparent age, that Sam was helping the defendant to supervise.
18.	At noon the training session finished.  Most of the boys went home. Beau at once went over to the inflatables to join his sister; Luke went with him.   They asked the defendant whether they could play on them and it has never been in dispute that, to them, she said yes. At first they played on the castle; then they tried the run.
19.	While, with the help of Mrs Clayton, the claimant’s father was collecting the balls and other equipment, the claimant and Simon asked him whether they could also go over and play on the inflatables.  He told them that they were for use at a private party and that they could not play on them. He gave them a ball to kick about instead.  Nevertheless after a few minutes they went over to the inflatables and, so the judge found, obtained the defendant’s permission to play on them.  By that time the defendant had moved from her position about 17' in front of both inflatables to a position up against the side of the run which was closer to the castle, namely about 18' from it.  She did so because Beau needed help in fastening the belt around himself.  So her back was turned from the castle.  She was in that position when she gave the permission to the claimant and Simon.  It was the defendant’s evidence that all the other children who had played on the run that morning, in particular her own children, had managed to fasten the belt around themselves without need for her assistance.  Nevertheless it seems from the evidence of Mrs Clayton that at times that morning, for some purpose or other, the defendant had moved over to the run while children were playing on the castle.
20.	The claimant and Simon took off their football boots and climbed on to the castle.  The evidence was unclear as to the number of other children who were on the castle while they were on it.  Sam was definitely on it.  James was probably on it.  One of the defendant’s daughters was possibly on it.  No one else was on it.
21.	The judge found that the accident happened “within a short time” of the advent of the claimant and Simon on to the castle; he did not attempt any analysis of the precise length of that period.  When the accident happened, the defendant was continuing to attend to Beau on the run and so her back continued to be turned from the castle.  In those circumstances the only witnesses who gave evidence of events on the castle following the advent of the claimant and Simon on to it were Simon himself and Sam.  It is clear that the judge generally found the evidence of Simon to be more credible than that of Sam.  In particular, of course, he accepted Simon’s evidence (which he described as clear and convincing) and rejected Sam’s evidence in relation to the issue whether the defendant had given the permission to the claimant and Simon.  In one of his written statements Simon said that the accident occurred within a couple of minutes of his advent, with the claimant, on to the castle.  When Mr Eklund put it to him that it occurred within only half a minute, Simon, in an answer upon which Miss Rodway relies, maintained that it occurred within one or two minutes and so largely adhered to his written statement.  The “short time” to which the judge referred is probably best measured by Simon’s evidence, although it calls for a substantial margin referable to honest error.
22.	At first the claimant and Simon bounced up and down on the castle.  Indeed at some stage the claimant’s father, who was about 55 yards away from the castle, saw their heads bobbing up above the side wall of it which faced towards him; he correctly assumed that they had obtained the defendant’s permission to play on it.  He could also see Sam standing on the castle; and, like Mrs Clayton, he assumed that Sam was helping the defendant to supervise.
23.	Very quickly the somersaulting began. Until Sam gave his oral evidence, there was a substantial dispute in relation to the sequence of events in this respect.  Simon’s evidence, written and oral, was that he did the first somersault (from left to right, if one faced the castle), that the claimant did the second (also from left to right) and that, “within a split second” and before the claimant was up on his feet, Sam did the third (from right to left).  Sam’s written evidence, by contrast, seemed to be to the effect that he did the one and only somersault prior to – as well as causative of – the accident. In his oral evidence, however, he said, first, that he could not remember somersaults on the part of the other boys and, ultimately, in the light of Simon’s evidence with which he considered that he could not disagree, he accepted that first Simon and then the claimant each did a somersault, with the result that he decided to do one himself.
24.	This leads us to a finding of fact on the part of the judge which, with respect, we consider on analysis to be unsafe.  The finding was that, before doing his somersault, Sam had announced “Look out. I’m going to do a somersault”. The judge referred to this announcement in the course of considering whether, had she been watching the children on the castle at that moment, the defendant would have been able to intervene in order to prevent the somersaults or at least Sam’s fateful somersault.  The judge considered that the fact that Sam had made such an announcement enhanced the probabilities of effective intervention on her part.  We consider the judge’s finding to be unsafe for three reasons, taken together:
(a)	Sam’s claim to have made the announcement was closely linked to his written evidence, later abandoned, to the effect that he alone had done a somersault. In that context an announcement that he was going to do one at least made sense.
(b)	By contrast, such an announcement was in effect inconsistent with the sequence of events described by Simon, ultimately accepted by Sam and found by the judge, namely rapid somersaults first by Simon, then by the claimant and then, almost instantaneously, by Sam himself.
(c)	In his oral evidence Simon firmly rejected the suggestion that Sam had made any such announcement. In that the judge primarily relied on Simon’s evidence in relation to events on the castle after his arrival there with the claimant, we consider that it was incumbent on the judge at least to refer to Simon’s contrary evidence and to explain his rejection of it before making any such finding.
In our view it is too simplistic for Miss Rodway to submit that, in that Sam was his witness, it is not open to Mr Eklund to complain about the judge’s acceptance of this part of his testimony.  Mr Eklund remains entitled to complain that the judge removed it from its original context and sought to insert it into a context in which it does not fit. However, for reasons that we shall give, we do not consider that this issue bears on the ultimate result.
THE JUDGMENT
25.	After setting out his findings of fact, the judge summarised the claimant’s allegations of failure to exercise reasonable care as follows:
“i) failure to maintain continuous supervision of those using the 	castle;
ii) failure to forbid children using the bouncy castle from doing 	flips and somersaults.
iii) failure to ensure that only children of similar size and 	weight played on the bouncy castle at the same time.”
26.	He then referred to three documents upon which Miss Rodway had relied in support of these allegations.
27.	The first document was the hire company’s Hire Agreement, which Mr Perry had signed that morning and which in evidence the defendant confirmed that she had also then seen.  Part of the agreement was in the following terms:
“FOR YOUR INFORMATION, SAFETY AND ENJOYMENT WE RECOMMEND THE FOLLOWING:
Ensure that the equipment is supervised at all times by a responsible person and any boisterous behaviour is stopped … 
No mix of children of different sizes, or with adults, on equipment unless specifically designed so.”
28.	The other two documents were not seen by the defendants and the judge did not hold that they should have seen them. Nonetheless he commented that their content was ‘instructive’. The first of these was entitled “Health and Safety Information Sheet 7”. It was to be found on the hire company’s website but its initial provenance was unclear. Of its 21 recommendations, three were as follows:
“17. The operator and attendants should watch the activity on the inflatable constantly. They should use a whistle or other signal and take action at the first sign of any misbehaviour.
18. Somersaults and rough play should not be allowed.
…
20. Larger, more boisterous users should be separated from the smaller ones.”
29.	The third document was entitled “TERMS AND CONDITIONS OF HIRE”, but it formed no part of the hire agreement. It also (so at any rate the judge understood) was to be found on the hire company’s website. It was issued by the British Inflatable Hirers Association. It appears to have constituted the Association’s recommendation to its members of the terms and conditions which they might choose to incorporate into their agreements with customers.  This impression is confirmed by its footnote:
“N.B. If you would like to obtain a much more detailed legal disclaimer (and more conditions of hire etc), you will need to …”
The document was entitled “Safety Instruction Sheet for customers when inflatable play equipment is delivered”.  Then it stated: “It is the responsibility of the customer … to ensure that all possible steps are taken to avoid damage to the inflatable.  Please ensure that the following safety instructions are followed”. Seventeen “safety instructions”, elsewhere described as “guidelines”, were then set out, of which three were as follows:
“7. A responsible adult must supervise the inflatable at all times. 
8. Ensure that the inflatable is not overcrowded, and limit the numbers depending on age and size of the children using it. If the children are colliding into each other then it is too overcrowded.
9. Try to avoid large children and small children from using the inflatable at the same time. Some require strict supervision.”
30.	The judge then set out his reasons for finding that the defendant had been in breach of her duty of care: 
“17. It was the underlying platform of the claimant’s case that the Perry’s were failing to maintain an appropriate level of supervision of the bouncy castle at the time when the claimant climbed on board and made use of it.  For this purpose it was submitted that a constant watch was required.  Use of the equipment manifestly brought risks in its train.  Supervision was needed to ensure that any new users removed their shoes which would otherwise be a danger to the users and the equipment.  More importantly, it was contended, continuous supervision was also necessary to police the way in which the equipment was used e.g. intervening as necessary to stop users sitting on the sides, hanging from the walls, or otherwise exposing themselves or others to the risk of physical injury.
18. It is of course true that Mrs. Perry was in attendance throughout.  But the difficulty in my judgment was that she had to supervise the use of two pieces of equipment at the same time, both of which in fact needed uninterrupted supervision.  In short, it was not possible to maintain a permanent look-out on both sets of equipment, the more so where supervision of the bungee run might include monitoring and even helping users strap themselves in. During this process, the supervisor’s back would be to the bouncy castle: indeed this is why Mrs Perry did not see the incident or the run up to it.
19. I appreciate that neither Mrs Clayton nor Mr Harris were concerned about the level of supervision. But their appreciation of the situation was not accompanied by immediate responsibility for the conduct of the party, let alone with any knowledge of the recommendations made by the hirer.  In the result, largely as a consequence of insufficient allowance being made for the demands of operating two items of equipment, I conclude that the level of supervision of the bouncy castle was inadequate.  In my judgment the standard of supervision needed to be all the greater given that the users were not of an age to appreciate the significant risks involved.
Somersaulting
20. But nonetheless the claimant must establish that the absence of a continuous watch was causative of the accident.  I did not understand it to be suggested that each user of the bouncy castle should have been told before using it not to attempt flips or somersaults, let alone that the Perry’s should have installed a notice to that effect.
21. There is no evidence to suggest that there had been any somersaulting or any unruly behaviour during the morning.  Furthermore, whilst it is true that the incident was not observed by Mrs. Perry when her attention was diverted by one of the boys on the bungee run, it is clear that it all happened very quickly.  The arrival of Simon and Sam led fairly quickly to their sequential somersault followed by Sammy Pring.  In the event that she or Mr Perry had been watching, would it have made any difference?
22. The complaint was that no-one was in a position to intervene to stop the activity as soon as Simon could be seen to try a ‘flip’.  Whilst it would have needed a fairly rapid response, it was Sammy Pring’s evidence that even if he had been merely told to be careful, he would have refrained.  The probabilities of such effective intervention are enhanced by Pring’s warning ‘Look out: I’m going to do a somersault’ which was not heard, let alone acted on.  It follows that I find the shortfall in supervision was causative of the accident.
Relative Size
23. I now turn to the matter of the marked disparity in age and more importantly size of Sammy Pring compared with the others using the bouncy castle and the claimant in particular Mrs Perry described Sammy Pring as a ‘gentle giant’.  Indeed by the time he came to give evidence he was by any standards an enormously tall boy.  He was three or four years older than the other children using the castle.  More to the point, at the time of the accident, he was probably more than a foot taller and substantially heavier than all the others.
24. The risks of damaging collision are manifestly enhanced by mixing children of different sizes on a bouncy castle.  Avoidance of such a situation is at the forefront of all the various recommendations for safe use.  I conclude that Sammy Pring should not have been allowed to use the bouncy castle at the same time as the younger and smaller children and that this too was causative of the accident.
25. For all these reasons I hold that the claimant has made out his case against the Perrys. ”
APPELLANTS’ SUBMISSIONS
31.	It is central to the argument in support of the appeal against the judge’s primary holding that he placed inordinate reliance on the three documents, the second and third of which the defendant never saw and could not reasonably be expected to have seen. Indeed a primary purpose of the third document seems to have been to protect hire companies from liability for such accidents as occur on their inflatables; another purpose seems to have been to protect the inflatables themselves from suffering damage. Mr Eklund submits that, while some of the recommendations, particularly in the first document, may help to illumine the standard of care reasonably to have been expected of the defendant, they were wrongly used by the judge so as to define that standard; and that the judge’s recourse to the documents was an improper substitute for a necessary analysis of whether, in all the circumstances, the defendant’s decision to turn her back on the children on the castle while she attended to Beau on the run – and to keep it turned for a short time – lay outside the parameters of reasonable care.
32.	Mr Eklund explains that, by his reference to all the circumstances, he includes the following:
(a)	The castle had been in use for about two hours.
(b)	Save perhaps at the beginning when Mr Perry may have acted as the supervisor, the defendant had been present there uninterruptedly.
(c)	There had been no problem in relation to the use of the castle, and in particular no boisterous behaviour and no somersaulting.
(d)	Sam was about a foot taller, and heavier, than the other children and thus in principle his presence to some extent heightened the risk that they might suffer an injury.
(e)	On the other hand the defendant knew Sam well and considered that he was responsible and indeed that, albeit a giant, he was gentle.
(f)	Neither Sam’s presence nor any other factor had – or should have – given rise to concern on the part of the defendant that morning about the safety of the children on the castle.
(g)	Mrs Clayton had also seemed (and she confirmed in evidence that indeed she was) content with the defendant’s level of supervision of the inflatables both while Liberty had been on the castle, even though at times the defendant had moved over to the run, and after Beau and Luke had begun to use the run.
(h)	James had (as had his sister) become 10 on that day and so was not a young child.
(i)	The defendant had just given permission to two other boys, namely the claimant and Simon, to go on to the castle.
(j)	The defendant could see that they were not young children – in fact they were both aged 11 – but she did not know them and so could not assess their level of responsibility.
(k)	The advent of the claimant and Simon on to the castle would not make it over-crowded.
(l)	Even if she continued to turn her back on it, the defendant remained only 18' away from the castle and was thus well within earshot of the children who were on it.
(m)	The need for her to continue to attend to Beau on the run was likely to continue only for a short time.
(n)	In that the likelihood of injury and the gravity of any such injury as might occur each helps to inform the conduct of the reasonably careful parent, the likelihood of injury to a child on the castle during that short time was minimal and the risk that any such injury would be of the gravity of that sustained by the claimant was entirely unforeseeable.
33.	Mr Eklund concedes Miss Rodway’s point that there was no emergency in relation to Beau and that it would have been open to the defendant at once to have ceased to attend to him and indeed to have instructed him to leave the run for the time being; and also open to her, instead, to have shouted to the children on the castle not to bounce on the castle, indeed perhaps to get off it altogether, until after she had ceased to attend to him. But, says Mr Eklund, the judge never reached the stage of asking whether, in all the above circumstances, the defendant’s conduct fell outside the parameters of reasonable care when she opted to take neither course but, rather, to continue to attend to Beau while allowing the children to continue to play on the castle. Mr Eklund submits that the defendant’s duty was indeed to “supervise”; that supervision entailed not a “continuous watch” but active oversight of the children on the inflatables and a readiness swiftly to address any problem which might arise and in particular to attend to the perceived needs of a child.
DISCUSSION
34.	Children play by themselves or with other children in a wide variety of circumstances. There is a dearth of case precedent that deals with the duty of care owed by parents to their own or other children when they are playing together. It is impossible to preclude all risk that, when playing together, children may injure themselves or each other, and minor injuries must be commonplace. It is quite impractical for parents to keep children under constant surveillance or even supervision and it would not be in the public interest for the law to impose a duty upon them to do so. Some circumstances or activities may, however, involve an unacceptable risk to children unless they are subject to supervision, or even constant surveillance. Adults who expose children to such circumstances or activities are likely to be held responsible for ensuring that they are subject to such supervision or surveillance as they know, or ought to know, is necessary to restrict the risk to an acceptable level. 
35.	In this case the defendant had hired a bouncy castle and a bungee run. The judge found that the defendant permitted the claimant to play on the castle. The difficult task facing the judge was to decide what precautions the defendant should reasonably have taken to protect against risks to which she knew, or ought to have known, children playing on the castle would be exposed. The task was difficult because neither judges nor parents are likely to have everyday familiarity with bouncy castles or bungee runs or such risks as they pose.
36.	In considering the precautions that should reasonably have been taken in relation to the bouncy castle the judge had regard to the contents of the Health & Safety Information Sheet and the BIHA standard conditions of hire, which he commented were ‘instructive’. We have concluded that there is force in Mr Eklund’s submissions that the judge should not have attached significance to these documents. What he should have done was to identify the standard of care required in the circumstances of this case on the basis of the facts of which the defendant knew or ought to have known. These could not include the contents of documents that the defendant neither saw nor ought to have seen.
37.	The defendant contended that the standard of care that she was required to show was that which a reasonably careful parent would show for her own children. The claimant contended that the duty was to act as would any reasonable provider and supervisor of these kind of inflatables for use by young children, although ‘it is hoped that it comes to the same thing’. We consider that it does. In the context of this case, the issue was what positive steps would a reasonable parent take for the safety of a child of the claimant’s age playing on a bouncy castle. The answer to this question must depend critically on the risks that the reasonable parent ought to foresee would be involved in the use of the castle. In considering that question the judge could and should properly have had regard to any relevant information in the Hire Agreement, which the defendant read, but not to the other two documents. As the judge wrongly had regard to those documents it falls to us to carry out the exercise that the judge should have performed. 
38.	The injury suffered by the claimant in this case was of horrifying severity. It resulted from contact between the claimant’s forehead and Sam’s unshod heel. The Hire Agreement recommended for ‘safety and enjoyment’ that the equipment should be supervised at all times and that boisterous behaviour should be stopped. This does not provide any information as to the possible consequences of boisterous behaviour. A reasonable parent could foresee that if children indulged in boisterous behaviour on a bouncy castle, there would be a risk that, sooner or later, one child might collide with another and cause that child some physical injury of a type that can be an incident of some contact sports. We do not consider that it was reasonably foreseeable that such injury would be likely to be serious, let alone as severe as the injury sustained by the claimant. 
39.	Not only was it not reasonably foreseeable that boisterous play on the bouncy castle would involve a significant risk of serious harm, there was no evidence before the judge, or before us, of the extent of the risk of injury actually posed by bouncy castles. If injuries such as that suffered by the claimant had been suffered by those playing on bouncy castles on even infrequent previous occasions we would expect the risk of such injuries to have been specifically drawn to the attention of those hiring them. 
40.	For these reasons, we consider that the standard of care that was called for on the part of the defendant was that appropriate to protect children against a foreseeable risk of physical harm that fell short of serious injury. We turn to consider the consequence of this conclusion on the findings of breach of duty made by the judge. 
Supervision
41.	If our appraisal of the risk that should have been foreseen by the reasonable parent is correct, there can be no justification for holding that the duty of care requires that children who are playing on a bouncy castle must be kept under constant surveillance. The recommendation in the Hire Agreement does not so suggest. It does not speak of preventing boisterous behaviour, but of stopping boisterous behaviour. The impression given is that a responsible adult should be in the vicinity of the castle to intervene if those playing on it get boisterous, but not that the supervisor has to be watching them continuously to ensure that their behaviour never becomes boisterous. That accords with the conclusion as to the requirement of reasonable care that we consider would be drawn by a parent in the absence of any express recommendation.
42.	We consider that the judge imposed an unreasonably high standard of care in holding that the bouncy castle required uninterrupted supervision and that the same was true of the bungee run. The defendant acted reasonably in concluding that she could supervise both at the same time. She could not reasonably have foreseen that, in turning to help strap in a child on the bungee run, she would expose the children playing on the bouncy castle to an unacceptable risk.
Somersaulting
43.	We are not convinced that the reasonably careful parent, in the absence of any express warning, would have concluded that children should not somersault on the bouncy castle. The documents which the defendant did not see warned against this, but it is not clear precisely why they warned that somersaults or back or front flips, should not be undertaken. It is at least possible that this was because experience had shown that the person performing the somersault or flip was at risk of some injury. In ignorance of such a warning we think it open to question whether the defendant would have been negligent had she knowingly permitted one child to perform a somersault at a time. Whether, had she been keeping those playing on the bouncy castle under constant surveillance she could have reacted in time to stop Sam performing a somersault while the claimant was still on the floor of the castle must be open to doubt.  At all events, in the light of our conclusion that the defendant was not obliged to keep those playing on the bouncy castle under continuous surveillance, this question is academic. Whether she could have prevented the accident or not, the fact is that it occurred during a short period when, without fault, she was concentrating her attention elsewhere.  
Relative size
44.	The judge observed that avoidance of mixing children of different sizes was ‘at the forefront of all the various recommendations for safe use’. This was not true of the only document that the defendant read – the Hire Agreement. This recommended:
“No mix of children of different sizes, or with adults, on equipment unless specifically designed so”
The significance of the words that we have emphasised is far from clear, but they do at least suggest that there are designs that cater for users of different sizes to play together. Furthermore, the bouncy castle in question was designed to accommodate adults.
45.	The judge made the point that the risk of a damaging collision is manifestly enhanced if children of different sizes play on the castle together. We are not convinced that the risk of a collision is enhanced, but we do accept that the larger the colliding child the greater the risk of injury. We do not accept, however, that this fact should automatically lead the careful parent to prevent children of different sizes using the castle together. Sam was known to the defendant as a responsible and gentle child, albeit very large for his age. He had been bouncing on the castle in the course of the morning with other children, including Liberty, aged 9 or 10. Liberty’s mother saw nothing untoward about this, albeit that she assumed that Sam was helping to supervise, and nothing occurred during the course of the morning to give rise to apprehension about Sam playing on the castle with smaller children.
46.	Once again we have reached the conclusion that the judge applied too high a standard of care when concluding that the defendant was in breach of duty in allowing Sam to play on the bouncy castle with children who were smaller in stature. 
47.	We have given our reasons at some length, but to a large extent a case of this nature properly turns on first impressions. The factual scenario is a simple one and the photographs give a very clear picture of the bouncy castle and the bungee run. The issue is whether a reasonably careful parent could have acted in the same way as the defendant. The case does not turn on expert evidence or special knowledge. Essentially we have had to place ourselves in the shoes of the defendant and consider the adequacy of her conduct from that viewpoint and with the knowledge that she had. Each of us had the same reaction to the facts. The defendant could not be held at fault for the way that she acted. The manner in which she was supervising activities on the bouncy castle and the bungee run accorded with the demands of reasonable care for the children using them. The accident was a freak and tragic accident. It occurred without fault.
48.	 For these reasons we allow this appeal.