Katy Guest: Spare us the public displays of tonsil hockey

A friend once told me that there is nothing wrong with snogging on the Tube, since snogging is not officially a sexual act. It is if you're doing it right, I told him. He still, apparently, snogs on the Tube. I don't know whether any of his girlfriends has yet found it remotely sexual.

I thought of him last week when I heard about the latest restrictions in Dubai, where sexual acts in public places are already deeply frowned upon. Last year, Brits Michelle Palmer and Vince Acors were arrested for allegedly having sex in the glamorous resort of Jumeirah Beach. Now, Dubai's rulers have gone further. The Arabic-language newspaper Al Emarat Al Youm, which has close ties to the ruling family, announced the intention to ban miniskirts and skimpy shorts outside private areas; playing loud music in public; and kissing, holding hands and other unnecessary public displays of affection. Good for them.

Anyone who saw the photographs last week of Kate Moss chewing the face of her long-suffering boyfriend Jamie Hince will surely agree that this sort of behaviour should be left at home. Moss has form: she was seldom seen out with the grubby little weirdo Pete Doherty without most of his head disappearing into her mouth. Now Hince, too, appears not to be feeding her enough; she can't seem to stop sucking on his molars.

Moss is, of course, a glittering fashion model known for her excesses and is obliged to be recklessly outré in public. It is her moral duty to engage in disturbingly sexual behaviour in front of cameras; her responsibility to wear teeny-tiny hotpants that do nothing to conceal her bony arse. In the average office and omnibus, however, different standards of behaviour are expected, and anybody turning up to work in their underwear here ought to be introduced to a burqa.

Unfortunately, these facts were lost on the couple I encountered on the 185 to Lewisham the other day. Disembarking at their destination, the pair stopped dead in front of the bus steps, causing a pile-up of queasy passengers behind as they tickled each other's tonsils for minutes. I wouldn't have minded but, like Hince, the boyfriend wasn't even that hot. I'm sure I have been keener on a man on many occasions than she was on him at that moment at Lewisham bus station. But I resisted the urge to jump his bones; I wasn't dragged up.

Likewise the couples on the Tube most Friday mornings, mussing their bedhead with hangovers, the slightly uglier partner always dribbling in the ear of the slightly more embarrassed partner in a simian display to other passengers: I got laid last night, aren't I clever? They must fear that if they didn't hold hands so clammily, the better-looking one might perhaps get away in the mêlée.

One result of an excess of flesh, as any properly dressed person knows, is an inversely proportional decrease in eroticism. It is hard to find someone alluring when you can read the washing instructions on their knickers. The same rules apply to the public exhibition of sex.

One of the most erotic sights I ever saw happened to be in Dubai, over tea on a restaurant terrace, as a handsome English intellectual and a veiled local woman, so beautiful that she made men quite sick with desire, fell visibly and violently in love. In the course of an evening, having drinks and conversation with their friends, they moved imperceptibly closer until the tips of their little fingers touched. A sandstorm blew up. The air crackled. Nothing, except fingertips, happened.

Why can't Kate Moss learn to be similarly restrained?