Tim Fountain &mdash playwright, teacher, chronic over-sharer &mdash has always been &ldquodetermined to rub people&rsquos faces in the detail of my sex life.&rdquo That&rsquos a lot of rubbing if you&rsquove slept with 5,000 people, and when his one-man show, Sex Addict, is panned as freakish, an introspective Fountain wonders if his jokey title actually reflects a real problem. He, therefore, embarks on a cross-country exploration of what constitutes &lsquonormal&rsquo British sexuality.

That&rsquos the &lsquowhy&rsquo. As for the &lsquowhat&rsquo, it looks as if behind every mild-mannered British publican or housewife or banker lurks a dominatrix in Hereford, a swinger in Blackpool, a dogging enthusiast in Glasgow, a sado-masochist in Manchester, a urine devotee in London, a cross-dresser in Hertfordshire, or a bestiality enthusiast in Hull.

Fountain follows his nose, and every intriguing lead in the UK, to conclude that normal is as normal does, and what the Internet has done for British sex is what the airplane has done for world travel. Want to float in urine Want to dress up as a fox and lie on a pile of other people dressed as animals and paw them affectionately There&rsquos a website and/or a club for anything and everything. On a perfectly humdrum night in the Abcat cinema, Fountain watches &ldquostraight men in a gay porn cinema watching straight porn whilst having sex with a man dressed as a woman, as an effeminate man cuddles up to a big butch straight guy three yards away.&rdquo

Although he finds many of his discoveries joyless and depressing, Fountain (as ambassador for British sex) maps sexual subcultures and their vocabularies with flair, and although he isn&rsquot a fabulous writer, he&rsquos an acute and often funny observer &mdash presumably more so if you get the heavily British pop culture references. Love it or hate it, you won&rsquot find it uninteresting. But don&rsquot come within ten yards of it, if you&rsquore a prude.