Sexual self-help came into its own in the Sixties, kicking off with Helen Gurley Brown's Sex and the Single Girl and the founding of her Cosmopolitan empire. Ten years later, The Joy of Sex recommended bored couples to look, not between their legs, but to their feet for sexual inspiration - the big toe, the book declared, was 'a magnificent erotic instrument'. In the Eighties, women's magazines suddenly discovered that sex was a powerful weapon in the ratings battle and titles pushed the boundaries of taste to their limits in their quest to carry the most risque articles about sex. The recent upsurge in DIY sex therapy came in , when the British Board of Film Classification granted an '18' certificate to Dr Andrew Stanway's video The Lovers' Guide which, along with its companion volumes, has since sold around , copies in the UK and a further , abroad. This opened the floodgates for more explicit sexual information so that now practically anything can be shown - even ejaculation - just so long as it is 'educational'.