There's stacks of evidence that both genders are having a lot more sex and are starting younger compared with even 20 years ago. However, virtually nothing is known about how the kind of sex we have might have changed: women more often on top? More three-in-a-beds? More cunnilingus? More blowjobs?

I believe the strongest anecdotal clue lies in changes in the way that young people dance. I can recall attending a party in Bradford-upon-Avon in 1970 with a mob of (male) schoolfriends. Having smoked a good deal of dope, we danced in the style then current. Our bodies rolled about like drunks on a ship in a storm. Hands were raised in the air and swung about chaotically. For much of the time, eyes were closed in a solipsistic union with Led Zeppelin or Pink Floyd or whatever.

We did Neil from the Young Ones proud, but the interesting thing was that in those days, for the most part, such exhibitionistic, wildly self-expressive, blatantly erotic dancing by girls was unknown (female readers aged 45 or over please note my use of 'for the most part': I am not saying that none of you used to boogie with the boys). While the odd one at a pop festival would take off her top and let it all hang out (having turned on and tuned in, etc etc), it was very much not de rigueur for girls to do more than shift from foot to foot in the prescribed, rather demure Top of the Pops fashion, occasionally giving their hair a flick.

I am sorry to say that this was a pretty fair reflection of what happened during sex. The man (ie me) would let rip until self-expressed and the woman was expected to lie back and think of England. As far as I know, this was the norm - certainly, none of my early sexual partners pointed out the now obvious inequity of such an arrangement.

While I do not doubt that many young men are equally premature and selfish today, I suspect that the women expect a great deal better and are not backward in complaining at such treatment. Apart from the far greater awareness of what's what fostered at school, in magazines and so forth, possible evidence for this comes from changes in dancing behaviour.

By the time I had sloped into my thirties, unbeknownst to me, a large number of London clubs had opened. In 1986, given the task of researching a TV series about sex, I was dispatched to them in search of luckless victims willing to speak to Paula Yates about it.

Compared with 1970, things had almost reversed. Now it was the boys who were the ones jiggling from side to side, looking a bit sheepish. The girls gyrated with all the confidence, ostentation and self-absorption displayed by the boys of yesteryear.

Alas, alack, I am unable to report from firsthand experience whether this translated into bed behaviour. But I should not be surprised if it did.

Next week: the causes of male gaiety.