'It is good of you to spare me the time, Dr Butter.' They were in the same writing room where only a couple of weeks previously he had obtained his first impressions of George Edalji.

The surgeon smiled. He was a handsome, grey-haired man about a decade older than Arthur. 'I am happy to. I am glad to have the opportunity of thanking the man who wrote' – and here there seemed to be a microscopic pause, unless it was only within Arthur's own brain – 'The White Company.'

Arthur smiled in reply. He had always found the company of police surgeons to be as agreeable as it was instructive.

'Dr Butter, I wonder if you would agree to talk on a frank basis. That is to say, I have great regard for your evidence, but I have various questions and indeed speculations to put before you. Everything you say will be treated in confidence, and I shall not repeat a single word without giving you the opportunity to endorse it, correct it, or withdraw it completely. Would that be acceptable?'

Dr Butter agreed, and Arthur led him, to begin with, through the parts of his evidence which were the least controversial, or at any rate irrefutable by the defence. The razors, the boots, the stains of various kinds.

'Did it surprise you, Dr Butter, that there was so little blood on the clothing, given what George Edalji was accused of doing?'

'No. Or rather, you are asking too large a question. If Edalji had said, Yes, I mutilated the pony, this is the instrument I did it with, these were the clothes I was wearing, and I acted by myself, then I would be competent to offer an opinion. And in those circumstances I would have to say to you that yes, I would be very surprised, indeed astonished.'

'But?'

'But my evidence was, as it always is, about what I found: this amount of mammalian blood on this garment, and so on. That was my evidence. If I cannot tell how or when it got there, I am unable to comment further.'

'In the witness box, of course not. But between ourselves…'

'Between ourselves, I would think that if a man rips a horse, there would be a lot of blood, and he would be unable to control where it fell, especially if the deed is done on a dark night.'

'So you are with me? He cannot have done it?'

'No, Sir Arthur, I am not with you. I am very far from with you. There is a wide expanse between the two positions. For instance, anyone going out deliberately to rip a horse would know to wear some kind of apron, just as slaughtermen do. It would be an obvious precaution. But a few spots might fall elsewhere, and escape notice.'

'No evidence of any apron was given in court.'

'That is not my point. I am merely giving you a different explanation from your own. Another might be that there were others present. If there were a gang, as has been suggested, then the young man might not have done the ripping himself, but might have been standing by, and a few drops of blood might have fallen on his clothes in the process.'

'Again, no such evidence was given.'

'But there was a strong suggestion of a gang, was there not?'

'There was deliberate mention of a gang. But not a shred of proof.'

'The other man who ripped his horse?'

'Green. But even Green did not claim there was a gang.'

'Sir Arthur, I quite follow your argument, and your desire for evidence to support it. I merely say, there are other possibilities, whether or not they were brought out in court.'

'You are quite right.' Arthur decided not to press further on this. 'May we talk instead about the hairs? You said in your evidence that you picked twenty-nine hairs from the clothing, and that when you examined them under the microscope they were – if I remember your words correctly – "similar in length, colour and structure" to those from the piece of skin cut from the Colliery pony.'

'That is correct.'

'"Similar". You did not say "exactly the same as".'

'No.'

'Because they were not exactly the same as?'

'No, because that is a conclusion rather than an observation. But to say that they were similar in length, colour and structure is, in layman's terms, to say that they were exactly the same.'

'No doubt in your mind?'

'Sir Arthur, in the witness box I always err on the side of caution. Between ourselves, and under the conditions you have proposed for this interview, I would assure you that the hairs on the clothing were from the same animal whose skin I examined under the microscope.'

'And from exactly the same part too?'

'I do not follow you.'

'The same beast, but also the same part of the beast, namely the belly?'

'Yes, that is true.'

'Now, the hairs on different parts of a horse or pony would vary in length, and perhaps thickness and perhaps structure. Hairs from the tail or mane, for example, would be different?'

'That is also true.'

'Yet all of the twenty-nine hairs you examined were exactly the same, and from exactly the same part of the pony?'

'Indeed.'

'Can we imagine something together, Dr Butter? Again, in complete confidence, within these anonymous walls. Let us imagine – distasteful as it might be – that you or I go out to disembowel a horse.'

'If I may correct you, the pony was not disembowelled.'

'No?'

'The evidence given was that it had been ripped, and was bleeding, and had to be shot. But the bowels were not hanging from the cut as they would have been had it been attacked differently.'

'Thank you. So, imagine we wish to rip a pony. We would have to approach it, calm it down. Stroke its muzzle, perhaps, talk to it, stroke its flank. Then imagine how we might hold it while we rip it. If we are to rip the belly, we might stand against its flank, perhaps put an arm over its back, holding it there while we reached underneath with whatever instrument we were using.'

'I do not know. I have never attended such a gruesome scene.'

'But you do not dispute that this is how you might do it? I have horses myself, they are nervous creatures at the best of times.'

'We were not in the field. And this was not a horse from your stables, Sir Arthur. This was a pit pony. Are not pit ponies notorious for their docility? Are they not used to being handled by miners? Do they not trust those who approach them?'

'You are right, we were not in the field. But indulge me for the moment. Imagine that the act was done as I described it.'

'Very well. Though of course it might have been done quite differently. If there was more than one person present, for example.'

'I grant you that, Dr Butter. And you must grant me in return that if the deed were done roughly as I described it, then it is inconceivable that the only hairs which ended up on the individual's clothing were all from the same place, namely the belly, which in any case is not where you would touch the animal to calm it. And further, the same hairs are found on different parts of the clothing – on both the sleeve and the left breast of the jacket. Would you not expect, at the very minimum, some hairs from another part of the pony?'

'Perhaps. If your description of events is the true one. But as before you offer only two possible explanations – that of the prosecution, and your own. There is a wide expanse between them. For instance, there might have been some longer hairs on the clothing, but they were noticed by the culprit and removed. That would not be surprising, would it? Or they might have blown away in the wind. Or again, there might have been a gang…'

Arthur then moved, very cautiously, towards the 'obvious' solution proposed by Wood.

'You work at Cannock, I believe?'

'Yes.'

'The piece of skin was not cut by you?'

'No, by Mr Lewis who attended the animal.'

'And it was delivered to you at Cannock?'

'Yes.'

'And the clothing was also delivered?'