A leading expert on sexual behaviour, Professor Kaye Wellings, commented on the marked change in attitudes to sex - especially among young women - that has occurred in the last decade. 'Women now have twice as many sexual partners as they did ten years ago. Back in 1990, women were quite censorious about one-night stands. That is not the case now. And people are reporting more sexual activity, having more sexual partners and having sex earlier than in the past. We are seeing an explosion of sexual life.'