If Paul was a reliable witness, and that ‘if’ contained multitudes, Aaron could think of no plausible way Wildsmith could have known about the circumstances in which he’d written his letter. He just got out of bed with another woman wasn’t the sort of thing psychics tossed out as guesses: it was far too specific. But to know it as fact would require the sort of surveillance Special Branch might provide for a Soviet spy.

This didn’t make any sense. None of the explanations he could think of made sense.

Sherlock Holmes said, When you have excluded the impossible, whatever remains, however improbable, must be the truth. It was impossible that Wildsmith could actually tell a child murderer or a recently unfaithful fiancé from their handwriting, therefore he must have dug up the information that would allow him to fake it. But surveillance of that quality took men and time and expertise, which was to say money. You might do it to impress a suitably influential client—Aaron had a vague idea that Paul’s ex-fiancée was a Bright Young Person—but the problem was, Wildsmith couldn’t have predicted he’d find anything to make such an outlay worth while. And if he had money to spend and wanted to make an impression on the smart set, why would he live in a miserable room in Pentonville rather than renting something decent, somewhere fashionable?

GK Chesterton had taken issue with the Holmes quotation. He’d said that if you told him the Prime Minister was haunted by a ghost, that was impossible, whereas if you told him that the Prime Minister had slapped Queen Victoria on the back and offered her a cigar, that was merely improbable, but he knew very well which of the two was more likely to be true.

Which was all very well, but Aaron didn’t believe in ghosts. He reminded himself of that several times as he walked home.

***

THE NEXT FEW DAYS WERE rather too busy for Aaron to worry about the graphologist’s impossible fraud. He had to appear in court for the prosecution of George ‘Dapper’ Melkin for unlawful killing.

Dapper, a violent brute with a penchant for flashy waistcoats, was of the Brummagem Boys, a Birmingham outfit that had an ongoing dispute with the local Sabini gang. A Sabini man, one James ‘Nippy’ Nicholls, had died following a recent fracas; Aaron had two eye witnesses and a bloodstained gentleman’s walking stick, hollowed out and the end filled with lead, to put Dapper on the spot.