Not long ago Prospect magazine asked me to write a profile of Peter Ackroyd. This was not at all an easy task. For a start, it meant reading, or rereading, several of the books in Ackroyd’s multitudinous output (the 32-volume list in the prelims of this latest one is woefully incomplete, by the way). Then it meant browsing through the equally large number of teasing interviews Ackroyd has given to newspapers over the past thirty years, in which hardly anything of a personal nature is ever let out beneath the arc light. Finally, at the instigation of the editor, who conceded that it would be like getting blood out of a stone, I had to ring up the subject himself. Ackroyd was polite but noncommittal. The piece duly appeared: comprehensive, (mostly) admiring and – to use that ancient Fleet Street cliché – ‘rather light on the quotes’.

And what bearing does any of this have on Ackroyd’s new novel – his 16th, I make it, and the first since 2008’s The Casebook of Victor Frankenstein? Well, rather a lot, as, remarkably for a writer who usually confines himself to the wilder margins of history and the reimagining