Behind every book that is published lies a hinterland its author knows only too well, though readers will never be aware of it. This is a haunted landscape, populated by the ghosts of things written and excised, crisscrossed with paths that were thoroughly explored but came to a dead end, and alive with the faint echoes of stories that were eventually left untold. The further in time you get away from a book, the dimmer the details of its hinterland become, but some features remain more distinct than others. For example, I still regret deleting from my biography of Christopher Isherwood a detailed account of the circumcision he underwent in his grandparents’ house shortly before his fifteenth birthday in 1919. The reasons for the cut – if I may use the term in this context – had nothing to do with prudery or squeamishness, both of which would be very thoroughly challenged elsewhere in the narrative; it was simply that this was an episode that could be neatly and easily removed. Given that the tardy surgical procedure seems to have had no lasting psychological effect on Isherwood, it was difficult to maintain that it was essential to include a description of it in a book that was already too long. I had, however, been rather fond of it, since it made use of my hard-won knowledge of the family’s medical history and drew upon the hilariously periphrastic account of the operation given by Isherwood’s mother in her diary.

Radical surgery was also performed (to its benefit) on another of my books, Housman Country, my editor wielding his scalpel with relish while I stood nervously beside him in my scrubs, occasionally emitting faint squeaks of protest. A long analysis of an obscure 1954 novel in which a convicted murderer