All we know about sex is that our parents did it. Once

There are lies, damn lies and the things people say about sex. The fibs they tell about size, frequency, habit and partners tumble so thick and fast and fluently from the human mouth, it's hard to believe we're not wired for sexual dishonesty. A recent survey tells us that Britons aged 50-plus are having the best sex of their lives. Are they, by gum! Not just good, but the very best? Better than when the first great, three-times-a-night passion of their lives set their bodies aflame and they suddenly realised why they'd been put on the planet?

There are lies, damn lies and the things people say about sex. The fibs they tell about size, frequency, habit and partners tumble so thick and fast and fluently from the human mouth, it's hard to believe we're not wired for sexual dishonesty. A recent survey tells us that Britons aged 50-plus are having the best sex of their lives. Are they, by gum! Not just good, but the very best? Better than when the first great, three-times-a-night passion of their lives set their bodies aflame and they suddenly realised why they'd been put on the planet?

Better than when the men folk didn't need Viagra and nobody's back made that strange cracking sound? Obviously that's far more plausible than the possibility that they bragged a little to a market researcher who had the impertinence to call just as they were snuggling up on the sofa with a flatulent cocker spaniel to watch Richard and Judy. If people didn't routinely lie about sex, we wouldn't have all those spurious statistics (a tautology, if ever I wrote one) whereby men claim to have had 25 partners by the time they're 30, while women have bedded only two, including their husband. You can only presume that there are a couple of generous-spirited souls out there who make Annabel Chong look like a rank amateur. Unless people are more like my circle of acquaintance. In which case women tend to cull unappetising specimens from their memory banks while men exaggerate every drunken cuddle until in their own minds they've bedded six supermodels and the woman from accounts who bears a passing resemblance to Felicity Kendal. The only things we truly know about sex is that our parents did it at least once and so, less appetisingly, did that couple from Big Brother.

Considering Joe Public's talent for sexual mendacity, it's amazing that we seem to think celebrities are duty bound to tell us every last secret of the bed chamber. Certain sections of the media are howling in rage at the possibility that Sven Goran Eriksson denied bedding a comely secretary. They are equally splenetic about Jemima Khan's and Hugh Grant's refusal to clarify their "friendship". This demand for carnal honesty is peculiar, not least for the fact that, when it comes to sex, denials are more eloquent than affirmations. "I did not have sexual relations with that woman" roughly translates as "She gave me the best blowjob in history". Clinton was merely following the social convention; in Edith Wharton's day they would have understood the subtext perfectly.

Frankly, there are few things more suspicious than celebrity avowals of fervid congress. Remember when Chris Evans claimed to be dating Geri Halliwell, or, more recently, Jordan's avowed passion for Peter Thingie from the jungle? Both relationships had the PR's ring of solid tin about them. Few confessions in recent times have been as suspect as Leslie Ash's and Lee Chapman's insistence that her hospitalisation was due to a particularly vigorous bout of lovemaking.

And even were it true, saying such things in public is so flesh-crawlingly creepy that you feel the need for stringent legislation to make such declarations offences against public decency. I like talking about sex as much as the next person - more than the next person, in all probability - but there's a difference between veiled frames of reference and incontinent self-confession.

In the natural order of things, sex is a mysterious and private pursuit. There is no obligation to confess your most intimate encounters to the outside world, and prurient employers and journalists should not have the temerity to quiz you on them. If someone asks "Are you an orgiast, Jones?", the correct answer, even if you were caught naked maypole dancing with the entire typing pool, is "No". Lies about sex should be exempt from all penalty clauses other than the traditional one where your spouse cuts your goolies off. Only partners are due some answers (though they often don't want them) and only they should be able to sack you. It is also worth remembering that many celebs lie about an affair not so much to save their skin, but to save their betrayed spouse from the further horror of public humiliation.

Surely it's time to release sex from the shackles of honesty and return it to its proper sphere - blissful and endless speculation.