Incredible love triangle that inspired The Joy of Sex: Manual was based on Dr Alex Comfort's own romps with his wife's best friend - as Bridget Jones director makes a film about their VERY complicated love life

Growing up as the son in a middle class family in Barnet, few could have predicted Alex Comfort, who had a striking fascination with molluscs, would have gone on to bring about a sexual awakening for millions around the world - but there were certainly signs of fire in the young teen's personality. At the age of 14, he blew up his hand and lost four fingers while experimenting with a new compound of gunpowder, leaving only his thumb remaining on his left hand. A few short years later, he won a place at Cambridge University where he studied medicine - and met his wife Ruth.

The conventional marriage to Ruth which bore a son, Nicholas, served both parties well until Ruth's university friend, Jane Henderson, re-entered their lives and began a passionate affair with the gerontologist. Their love triangle led to the publication of revolutionary book The Joy of Sex: A Gourmet Guide To Lovemaking in 1972, which will now be introduced to a whole new audience by way of a film of the same name, being made by Bridget Jones director Sharon Maguire.

Comfort's book, a manual to having better sex which featured groundbreaking illustrations of the positions in which he made love to Jane, has sold more than 12 million copies and been translated into 30 languages. However, it also brought about the end of his marriage to Ruth, who saw the manual as a public humiliation of how her husband romped wildly with her best friend - in contrast to her more conservative sexual values.

The love triangle between Comfort, Ruth and Jane; eventually saw the gerontologist leave his wife to marry his lover and move to California where he could engage in the libertine lifestyle he believed would save humanity. Speaking to the Guardian, Maguire said the complicated relationship that brought Comfort huge success by inspiring the book had also contributed to 'the unravelling of his life'. The Joy of Sex, published in 1972, became a revolutionary manual for couples around the world to improve their sex lives.

She said: 'The clashing psychologies of the three characters makes for this fascinating conundrum about love and sex and relationships that’s wrapped up in a comedy.'. Comfort and Ruth's son Nicholas, who now lives a quiet life in south east London with his third wife, opened up about how his father's extramarital affair had played out before he wrote The Joy of Sex. Speaking to the Daily Mail in 2022, he said: 'My mother was not the most tactile of people and Jane, presumably, was.

'Dad was dividing his time between mum and Jane and this arrangement almost became a fixed state. 'But then his research work (into gerontology, the study of ageing) at University College London came to an end, he went to America and 'Joy' came out. 'Dad told me later there were quite a few gerontologists at Sandstone. He said all of them had a chronic fear of their own mortality which made them want to enjoy life more.'.

The book, published in 1972, featured detailed illustrations of sex positions he used to experiment with Jane (a Plan B, after Comfort initially took Polaroids of himself having sex with Jane to horrified publishers). Dr Alex Comfort had a conventional family life with his wife Ruth, and their son Nicholas for many years after the couple met at Cambridge University (Family pictured in 1966). As a librarian, her role was cataloguing the many twists and turns of their adventurous sex life.

They also tried hiring pornographic models but they kept pouting seductively and didn't match up to the image of average, loving couples. The illustrations were in part modelled on Charles Raymond, one of the illustrators, and his wife Edeltraud; while also featuring Indian and Japanese classic erotica. The publishing decision was taken over fear of obscenity lawsuits. Bearded Charles, one of the artists on the book (he usually painted flowers), and German-born Edeltraud, volunteered to recreate Comfort and Henderson's sex life 'and she got him through the positions with Teutonic efficiency', said Nick.

The sex was not simulated, but real, he says, and took place in a freezing cold garret which could not be heated because of the miners' strike. 'They were trying to do 200 different poses and it was during the power cuts,' said Maguire. 'Although it sounds like a sex romp, it was all well-intentioned, because there really was nothing like it. No textbooks, even medical ones, no illustrations, no pictures.'.

When the book came out, it also made a star of 'Hairy Man', the hirsute lover  depicted adopting all sorts of extraordinary positions with his lover. Modelled on a cookery book. Its sub-title was A Gourmet Guide and the section titles were Starters, Main Courses and so on. Dr Alex Comfort became known as 'Dr Sex' after the book became a worldwide sensation in the 1970s. The gerontologist met his wife Ruth at Cambridge University; before engaging in an affair with her university friend Jane decades later - inspiring him to write the book.