The Imitation Game, the new movie in which Benedict Cumberbatch plays the prodigal computer pioneer Alan Turing, opens an uncomfortable window on the still-festering swamp of British sexual behavior. When I saw the movie in London there was a palpable frisson of disgust from the audience on learning how Turing had been treated by the country he had served with enormous distinction in World War II.

In 1952, Turing was found guilty on three counts of “gross indecency contrary to Section II of the Criminal Law Amendment Act of 1885”—a law that had its first sensational effect in the trial of Oscar Wilde. Turing had not contested the charges—he gave an explicitly detailed admission of them. He had invited a 19-year-old drifter named Arnold Murray to his house and they had had consensual sex.

Murray had not made a complaint—Turing had triggered a police investigation himself by reporting a petty burglary at his house that, it transpired, had been carried out by an acquaintance of Murray’s. The stolen items included a shirt, some fish knives, a pair of trousers, shoes, shavers, a compass, and an open bottle of sherry.