For women, the average age for a first experience of penetrative sex fell from 21 to 17, while among men the corresponding ages went down from 20 to 17, the research covering 19,000 people aged 19 to 59 revealed.
Significantly though, the team led by Kaye Wellings, research fellow of the London School of Hygiene and Tropical Medicine, found that the lower age could not be attributed solely to the greater sexual freedom brought about by the Pill as half of the decline was recorded during the 1950s.
One of the starkest statistics to come out of the National Survey of Sexual Attitudes and Lifestyles was the dramatic increase in the proportion of women who had sex before they were 16.
Fewer than 1 per cent of women over the age of 55 said they had sex before their 16th birthday; the proportion today is almost 20 per cent for women, and 25 per cent for men. Almost 50 per cent of women reported using a condom during the first sexual encounter, with 24 per cent on the Pill.
However, when researchers questioned women in the 16 to 24 age group who had sex before they were 16, half said they believed the experience had come too early. Even among those who began slightly later, 37 per cent felt they should have waited longer.
A number of factors seem to have influenced those beginning their sex lives before they felt ready. Peer group pressure was a strong influence, and alcohol was certainly implicated, but the team discovered that ignorance was a problem. The study found that those who received soundly-based sex education in school, rather than from parents or friends, often postponed their first sexual experience.
While the team concludes that compared to previous generations young people have more varied sexual experience, in terms of repertoire of sexual practices and the number of partners, the vast majority are monogamous - either sticking with one partner or moving consecutively between partners.