You might have supposed that Martin Amis’s enthusiasm for smoking would have diminished following the well-publicised death of his perpetually puffing best pal Christopher Hitchens. But there he was in the Sunday Times this week singing the praises of the weed and advancing the myth that it is conducive to creativity.

He told interviewer Clio Williams: “I smoke about ten a day . . . It’s an integral part of the writing process: apparently smoking can up your IQ by one-and-a-half points, and sometimes you need all the help you can get.”

As a one-time heavy smoker myself, I know this to be nonsense — and dangerous nonsense.

Perhaps the best known proponent of smoking at present is the artist David Hockney. In his time he was known, too, as the besotted lover of Peter Schlesinger, who features in Hockney’s Californian swimming pool paintings and A Bigger Splash (right), the film made about their creation.

That said, it might be instructive for Hockney to have his attention drawn to newly published diaries kept by his friend Christopher Isherwood. In Liberation (Chatto & Windus, £30) he would read Peter’s comments following their break-up: “I’ve never lived by myself so it’s quite exciting. I read again at night in bed. Little things like that I could no longer do, we led a very busy social life and lots of smoking which also gets me down”.