'I was just listening, Sir Arthur.'

'No, you were looking dubious. I can recognize dubiety when I see it. Come on, give me the obvious question.'

Wood sighed. 'I was only wondering whether George's eyesight might not have deteriorated in the course of three years' penal servitude.'

'Aha! I guessed you might be thinking that. Absolutely not the case. George's blindness is a permanent structural condition. That's official. So it was just as bad in 1903 as it is now. And he didn't even have glasses then. Any further questions?'

'No, Sir Arthur.' Although there was a lurking observation he did not think fit to raise. His employer might indeed never have met with such a degree of astygmatic myopia in all his days as an oculist. On the other hand, Wood had many times heard him regale a dinner table with the story of how he boasted the emptiest waiting room in Devonshire Place, and how his phenomenal lack of patients had given him time to write his books.

'I think I shall ask for three thousand.'

'Three thousand what?'

'Pounds, man, pounds. I base my calculation on the Beck Case.'

Wood's expression was as good as any question.

'The Beck Case, surely you remember the Beck Case? Really not?' Sir Arthur shook his head in mock disapproval. 'Adolf Beck. Of Norwegian origin as I recall. Convicted of frauds against women. They believed him to be an ex-convict by the name of – would you believe it? – John Smith, who had previously served time for similar offences. Beck got seven years' penal servitude. Released on licence about five years ago. Three years on, rearrested again. Convicted again. Judge had misgivings, postponed sentence, and in the meantime who should turn up but the original fraudster Mr Smith. One detail of the case I do recall. How did they know Beck and Smith were not one and the same person? One was circumcised and the other wasn't. On such details does justice sometimes hang.

'Ah. You are looking even more puzzled than at the beginning. Quite understandable. The point. Two points. One, Beck was convicted on the mistaken identification of numerous female witnesses. Ten or eleven of them, in fact. I make no comment. But he was also convicted on the clear evidence of a certain expert in forged and anonymous handwriting. Our old friend Thomas Gurrin. Obliged to present himself to the Beck Committee of Inquiry and admit that his testimony had twice condemned an innocent man. And scarcely a year before this confession of incompetence he had been swearing himself black and blue against George Edalji. In my view he should be barred from the witness box and every case in which he has been involved should be reexamined.

'Anyway, point two. After the Committee's report, Beck was pardoned and awarded five thousand pounds by the Treasury. Five thousand pounds for five years. You can work out the tariff. I shall be asking for three thousand.'

The campaign was advancing. He would write to Dr Butter requesting an interview; to the Headmaster of Walsall School to enquire about the boy Speck; to Captain Anson for the police records in the case; and to George to check if he had ever had any contentious business in Walsall. He would look up the Beck Report to confirm the extent of Gurrin's humiliation, and formally demand of the Home Secretary a new and final investigation into the entire matter.

He planned to devote the next couple of days to the anonymous letters, trying to make them less anonymous, seeking to progress from graphology to psychology to possible identity. Then he would turn the dossier over to Dr Lindsay Johnson for professional comparison with examples of George's handwriting. Johnson was the top man in Europe, having been called by Maître Labori in the Dreyfus Case. Yes, he thought: by the time I have finished I shall make the Edalji Case into as big a stir as they did with Dreyfus over there in France.

He sat at his desk with the bundles of letters, a magnifying glass, a notebook and his propelling pencil. He took a deep breath and then slowly, cautiously, as if watching for some evil spirit to escape, he undid the ribbons on the Vicar's parcels and the twine on Brookes's. The Vicar's letters were dated in pencil and numbered in order of receipt; those of the ironmonger were in no evident sequence.

He read them through in all their poisonous hatred and leering familiarity, their boastfulness and their near insanity, their grand claims and their triviality. I am God I am God Almighty I am a fool a liar a slanderer a sneak Oh I am going to make it hot for the postman. It was risible, yet risibility on risibility amounted to cruelty of a diabolical kind, under which the very minds of the victims might have broken down. As Arthur read on, his anger and disgust began to quieten, and he tried to let the phrases soak into him. You dirty sneaks you want twelve months penal servitude… I am as sharp as sharp can be… You great hulking blackguard I have got you fixed you dirty Cad you bloody monkey… I know all the toffs and if I have got a dare devil face it is no worse than yours… Who pinched those eggs on Wednesday night why you did or your man but I don't think they would hang me…

He read and reread, sorted and re-sorted, analysed, compared, annotated. Gradually, hints turned to suspicions and then to hypotheses. For a start, whether or not there was a gang of rippers, there certainly appeared to be a gang of writers. Three, he posited: two young adults and a boy. The two adults seemed at times to run into one another, but there was, he judged, a distinction to be made. One was solely malicious; while the other had outbursts of religious mania which veered from hysterical piety to outrageous blasphemy. This was the one who signed himself Satan, God and their theological conjoining, God Satan. As for the boy, he was exceedingly foul-mouthed, and Arthur put his age at between twelve and sixteen. The adults also bragged of their powers of forgery. 'Do you think we could not imitate your kid's writing?' one of them had written to the Vicar in 1892. And to prove it, there was a whole page elaborately covered with the plausible signatures of the entire Edalji family, of the Brookes family, and of others in the neighbourhood.

A large proportion of the letters were on the same paper, and had arrived in similar envelopes. Sometimes one writer would begin and then give way to another: the effusions of God Satan would be followed on the same page by the rough scrawl and rude drawings – rude in every sense – of the lad. This would strongly suggest that all three of them lived under the same roof. Where might this roof be? Since a number of the letters had been hand-delivered to their victims in Wyrley, it was reasonable to assume a proximity of not much more than a mile or two.

Next, what sort of roof might shelter three such scribes? Some establishment housing young males of different ages? A cramming school, perhaps? Arthur consulted educational directories, but could find nothing within any plausible distance. Could the malefactors be three clerks in an office, or three assistants in a business? The more he considered the matter, the more he was driven to conclude that they were members of the same family, two older brothers and a younger one. Some of the letters were extremely long, which argued for a household of idlers with time on their hands.

He needed more specifics. For instance, Walsall School seemed to be a constant factor in the case, yet how important a factor? And then, what about this letter? The religious maniac was quite evidently alluding to Milton. Paradise Lost, Book One: the fall of Satan and the burning lake of Hell, which the writer announced as his own final destination. It certainly would be if Arthur had his way. So, here was a further question for the Headmaster: had Paradise Lost ever been on the syllabus at the school, if so when, and how many boys had studied it, and did any of them take it especially to heart? Was this clutching at straws, or exploring every possibility? It was hard to tell.