Arthur leaned forward. 'Harry, would you be prepared to help us clear your friend and old schoolfellow's name?'

Harry Charlesworth noted the lowered voice and cajoling tone, but was suspicious of it. 'He was never exactly my friend.' Then his face brightened. 'Of course, I'd have to take time off from the dairy…'

Arthur had initially ascribed a more chivalrous nature to Harry Charlesworth, but decided not to be disappointed. Once a retainer and fee structure had been agreed, Harry, in his new capacity as assistant consulting detective, showed them the route George was supposed to have taken that drenching August night three and a half years previously. They set off across the field behind the Vicarage, climbed a fence, forced their way through a hedge, crossed the railway by a subterranean passage, climbed another fence, crossed another field, braved a clinging, thorny hedge, crossed another paddock, and found themselves on the edge of the Colliery field. Three-quarters of a mile at a rough guess.

Wood took out his pocket watch. 'Eighteen and a half minutes.'

'And we are fit men,' commented Arthur, still plucking thorns from his overcoat and wiping mud from his shoes. 'And it is daylight, and it is not raining, and we have excellent eyesight.'

Back at the dairy, after money had changed hands, Arthur asked about the general pattern of crime in the neighbourhood. It sounded routine: theft of livestock, public drunkenness, firing of hayricks. Had there been any violent incidents apart from the attacks on farmstock? Harry half-remembered something from around the time George was sentenced. An attack on a mother and her little girl. Two fellows with a knife. Caused a bit of a stir, but never went to court. Yes, he would be happy to look into the matter.

They shook hands, and Harry walked them to the ironmonger's, which also served as the grocery, the drapery and the Post Office.

William Brookes was a small, rotund man, with bushy white whiskers counterbalancing his bald cranium; he wore a green apron stained by the years. He was neither overtly welcoming nor overtly suspicious. He was about to take them into a back room when Sir Arthur, nudging his secretary, announced that he was in great need of a bootscraper. He took an intense interest in the choice on offer, and when purchase and wrapping were complete, acted as if the rest of their visit was just a happy afterthought.

In the storeroom, Brookes spent so long digging around in drawers and muttering to himself that Sir Arthur wondered if he might have to buy a zinc bath and a couple of mops to expedite matters. But the ironmonger eventually located a small packet of heavily creased letters bound with twine. Arthur immediately recognized the paper on which they were written; the same cheap notebook had served for the letters to the Vicarage.

Brookes recalled, as best he could, the failed attempt at blackmail all those years ago. His boy Frederick and another boy were meant to have spat upon some old woman at Walsall Station, and he had been instructed to send money to the Post Office there if he wanted to avoid his son being prosecuted.

'You did nothing about it?'

'Course not. Look at the letters for yourself. Look at the handwriting. It was just a prank.'

'You never thought of paying?'

'No.'

'Did you think of going to the police?'

Brookes gave a scornful puff of the cheeks. 'Not for a moment. Less than a tenth of a moment. I ignored it, and it went away. Now the Vicar, he was all of a pother. Went around complaining, writing to the Chief Constable and all that, and where did it get him? Just made it all worse, didn't it? For him and his lad. Not that I'm blaming him for what happened, you understand. Just that he's never understood this sort of village. He's a bit too… cut and dried for it, if you know what I mean.'

Arthur did not comment. 'And why do you think the blackmailer picked on your son and the other boy?'

Brookes puffed his cheeks again. 'It's years now, sir, as I say. Ten? Maybe more. You should ask my boy, well, he's a man now.'

'Do you remember who this other boy was?'

'It's not something I've needed to remember.'

'Does your boy still live locally?'

'Fred? No, Fred's long left. He's in Birmingham now. Works on the canal. Doesn't want to take on the shop.' The ironmonger paused, then added with sudden vehemence, 'Little bastard.'

'And might you have an address for him?'

'I might. And might you want anything to go with that bootscraper?'

Arthur was in high good humour on the train back to Birmingham. Every so often he glanced at the three parcels beside Wood, each of them wrapped in oiled brown paper and tied with string, and smiled at the way the world was.

'So what do you think of the day's work, Alfred?'

What did he think? What was the obvious answer? Well, what was the true answer? 'To be perfectly honest, I think we've made not very much progress.'

'No, it's better than that. We've made not very much progress in several different directions. And we did need a bootscraper.'

'Did we? I thought we had one at Undershaw.'

'Don't be a spoilsport, Woodie. A house can never have too many bootscrapers. In later years we shall remember it as the Edalji Scraper, and each time we wipe our boots on it we shall think of this adventure.'

'If you say so.'

Arthur left Wood to whatever mood he was in, and gazed out at the passing fields and hedgerows. He tried to imagine George Edalji on this train, going up to Mason College, then to Sangster, Vickery amp; Speight, then to his own practice in Newhall Street. He tried to imagine George Edalji in the village of Great Wyrley, walking the lanes, going to the bootmaker, doing business with Brookes. The young solicitor – well-spoken and well-dressed though he was – would cut a queer figure even in Hindhead, and no doubt a queerer one in the wilds of Staffordshire. He was evidently an admirable fellow, with a lucid brain and a resilient character. But if you merely looked at him – looked at him, moreover, with the eye of an ill-educated farm-hand, a dimwit village policeman, a narrow-minded English juror, or a suspicious chairman of Quarter Sessions – you might not get beyond a brown skin and an ocular peculiarity. He would seem queer. And then, if some queer things started happening, what passed for logic in an unenlightened village would glibly ascribe the events to the person.

And once reason – true reason – is left behind, the farther it is left behind the better, for those who do the leaving. A man's virtues are turned into his faults. Self-control presents itself as secretiveness, intelligence as cunning. And so a respectable lawyer, bat-blind and of slight physique, becomes a degenerate who flits across fields at dead of night, evading the watch of twenty special constables, in order to wade through the blood of mutilated animals. It is so utterly topsy-turvy that it seems logical. And in Arthur's judgement, it all boiled down to that singular optical defect he had immediately observed in the foyer of the Grand Hotel, Charing Cross. Therein lay the moral certainty of George Edalji's innocence, and the reason why he should have become a scapegoat.

In Birmingham, they tracked Frederick Brookes down to his lodgings near the canal. He assessed the two gentlemen, who to him smelt of London, recognized the wrapping of the three parcels under the shorter gentleman's arm, and announced that his price for information was half a crown. Sir Arthur, accustoming himself to the ways of the natives, offered a sliding scale, rising from one shilling and threepence to two and sixpence, depending on the usefulness of the answers. Brookes agreed.

Fred Wynn, he said, had been the name of his companion. Yes, he was some relation to the plumber and gas-fitter in Wyrley. Nephew perhaps, or second cousin. Wynn lived two stops down the line and they went to school together at Walsall. No, he'd quite lost touch with him. As for that incident all those years ago, the letter and the spitting business – he and Wynn had been pretty sure at the time it was the work of the boy who broke the carriage window and then tried to blame it on them. They'd blamed it back on him, and the officers from the railway company had interviewed all three of them, also Wynn's father and Brookes's father. But they couldn't work out who was telling the truth so in the end just gave everyone a warning. And that was the end of it. The other boy's name had been Speck. He'd lived somewhere near Wyrley. But no, Brookes hadn't seen him for years.