Keeping a mistress was essential to John le Carré’s success

Adam Sisman is sensitive to the charge that a book about an author’s unknown mistresses is simply an exercise in prurience. ‘I am not one of those who believes sex explains everything,’ he declares defensively.

But this admirably concise volume justifies its title. Sub-themes such as the practice and ethics of biography, and the emotional toll taken by spying, run through it. But its core relates how, when writing his 2015 life of David Cornwell (John le Carré’s real name.) Sisman was prevailed upon to delete details of his subject’s many extramarital affairs. In fraught pre-publication negotiations, he met Cornwell’s son Stephen, who suggested he keep this material as a ‘secret annexe’ to appear later.

This is that ‘annexe’ (everything seems to require the adjective ‘secret’). Sisman argues plausibly that Cornwell’s career in intelligence was uneventful, and well covered in his biography.