It wasn’t the one in the 1960s. Historian Faramerz Dabhoiwala argues that the real Sexual Revolution occurred in the 18th century,  and we’re still working out the consequences of that one. Excerpt:
The most obvious change was a surge in pre- and extramarital sex. We can measure this, crudely but unmistakably, in the numbers of children conceived out of wedlock. During the 17th century this figure had been extremely low: in 1650 only about 1% of all births in England were illegitimate. But by 1800, almost 40% of brides came to the altar pregnant, and about a quarter of all first-born children were illegitimate. It was to be a permanent change in behaviour.
Just as striking was the collapse of public punishment, which made this new sexual freedom possible. By 1800, most forms of consensual sex between men and women had come to be treated as private, beyond the reach of the law. This extraordinary reversal of centuries of severity was partly the result of increasing social pressures. The traditional methods of moral policing had evolved in small, slow, rural communities in which conformity was easy to enforce. Things were different in towns, especially in London. At the end of the middle ages only about 40,000 people lived there, but by 1660 there were already 400,000; by 1800 there would be more than a million, and by 1850 most of the British population lived in towns. This extraordinary explosion created new kinds of social pressures and new ways of living, and placed the conventional machinery of sexual discipline under growing strain.
Urban living provided many more opportunities for sexual adventure. It also gave rise to new, professional systems of policing, which prioritised public order. Crime became distinguished from sin. And the fast circulation of news and ideas created a different, freer and more pluralist intellectual environment.
Thanks to Liam, the reader who sent that link. Fascinating story.