In the 1970s a ‘nude biologist brandishing a cigar’ wrote a game-changing sex manual. Now, ‘Shazza’ is putting his story on the big screen

Sex positivity, polyamory, threesomes: they may not be universal practices but the extent to which they are more acceptable these days has a lot to do with a largely forgotten British polymath called Alex Comfort. In 1972, the physician, expert on molluscs and gerontologist published The Joy of Sex, the first popular book in the English language that explained and celebrated the art of making love.

A coffee table how-to guide with tasteful drawings of a naked couple in an imaginative range of sexual positions, it became a huge international bestseller and helped shift perceptions of sex some way along the procreational-recreational axis.