In the wake of Sunday's expose of Judge Thornton, Angela Lambert argues that media intrusion is on the verge of destroying the notion of a private life; Commercial sex is not something of which men are proud - otherwise they might discuss it as openly as they do fast cars and gambling
`In private, a person says all sorts of things, slurs friends, uses coarse language, acts silly, tells dirty jokes, repeats himself, makes a companion laugh by shocking him with outrageous talk, floats heretical ideas he'd never admit in public, and so forth ... but that we act differently in private from the way we do in public is everyone's most conspicuous experience; it is the very ground of the life of the individual. Curiously, this obvious fact remains unconscious, unacknowledged, forever obscured by lyrical dreams of the transparent glass house, it is rarely understood to be the value one must defend beyond all others. Private and public are two essentially different worlds and respect for that difference is the indispensable condition for a man to live free. The curtain is not to be tampered with, and curtain-rippers are criminals. When it becomes the custom and the rule to divulge another person's private life, we are entering a time when the highest stake is the survival or the disappearance of the individual.'

Milan Kundera, New York Review of Books, September 1995

It sounds extreme. Kundera's words were probably written with a memory of totalitarian Communism in mind. Yet they have a troubling relevance to our world today, in which the media - as much as the state - increasingly intrudes upon the private realm in the name of the public interest.

Take the case of Judge Anthony Thornton, caught by a secret video camera with two prostitutes and, it is alleged, some drugs. If Judge Thornton is forced to resign, following publication last Sunday of stills from the tape in the News of the World, the roll call of public figures toppled simply for having sex and paying for it will gain another name.

Earlier this month Peter Hobson, the then headmaster of Charterhouse School, resigned after finding himself exposed for visiting a call girl in Guildford. Hugh Grant seems to have survived exposure of his meeting with Divine Brown, perhaps because he owned up so becomingly on an American chat show and was given such a hard time for his indiscretion by La Hurley in private. A few years ago, Sir Allan Green, then Director of Public Prosecutions, was brought low because he was discovered kerb-crawling in King's Cross. His wife later committed suicide.

These men have fallen because they punctured the myth that married men live in a perpetual state of fidelity. If caught with a prostitute, they are disgraced and humiliated for an act that is still treated as a rare and shocking lapse from universal standards of moral decency. These moral standards, which the tabloids defend, are no more than a device, put in place to allow us to feel morally self-righteous when hungrily devouring the salacious details. For without a semblance of a moral purpose, this fare would be exposed for what it is: a malicious intrusion, for the sake of little more than gossip, into something that should remain strictly private.

We are trapped in a moral and legal no-man's land in this country. Prostitution is not legalised, yet in genteel Edinburgh there are about 400 women at work in saunas or massage parlours, earning pounds 2,000 per month, according to a recent survey. "Trying to stop prostitution is like trying to compress water: all you do is displace it. It will come squeezing out of the sides somewhere else," says Tom Wood, assistant chief constable of Lothian and Borders police.

In Britain, we persist with the presumption that middle-aged married men only make love to their wives - that is, if they haven't given up sex altogether. Yet some countries have, unexpectedly, legalised prostitution. We all know about broad-minded Holland and hygiene-obsessed Germany, but prim and proper Switzerland? Prostitution was legalised there in December 1994, with the introduction of plush new purpose-built brothels. It was effectively recognised in Australia four years ago with state-inspected brothels. And, according to a poll conducted in January, most French people (68 per cent) want brothels legalised again - 50 years after they were closed in the aftermath of the Second World War.

Few studies of sexual behaviour have addressed the question of how many men pay for sex, and if they do, how frequently. The probable reason for this lack of reliable data is that paid sex is stigmatised: perhaps because it is associated with the transmission of venereal disease, or because it suggests that the man is too inadequate to find a partner willing to give him sex for free.

Kinsey's mainly white-collared research in the late Fifties, carried out among his American compatriots, showed that about 30 per cent admitted having had contact with a prostitute at least once. In Britain, a survey called Sexual Attitudes and Lifestyles, carried out in 1994, published by Blackwell Scientific Publications, reported that 6.8 per cent of men said they had paid for sex with a woman at some time.

In the case of single young men, the survey found that only about 4.1 per cent had paid for sex. Among older, more sexually experienced men, the proportion rose to 10.3 per cent. It was highest among widowed, separated or divorced men, of whom 14.2 per cent reported having paid for sex at some time.

Prostitution is one of the great unknown subjects for women (except those actually engaged in the profession), perhaps because it is the one about which men, motivated by guilt and vanity, are most likely to lie to their female partners. Greater equality between the sexes, and the openness with which sexual matters are discussed, means that women are no longer wholly naive about men's secret needs and preferences. But commercial sex is not something of which men are proud - otherwise they might discuss, if only among themselves, paying for sex as openly as they discuss buying alcohol, or other dangerous thrills such as fast cars and gambling.

The reason they do not is that unlike driving a car, having sex is deeply personal. We all protect our most private behaviour. It is into this area that the moralists go charging, applauding themselves for "protecting" us - "innocent" women, schoolboys, wives, families - from moral contamination.

Men go to prostitutes, or so I have always assumed, because they must, to discharge sexual needs for which they have no other outlet, and pay for sex only because they cannot obtain it free. Those with unusual sexual desires sometimes manage to suppress them; others indulge them single- handed (so to speak), but a great many look for a paid partner prepared to offer the kind of sex they want. Lucky is the man whose sexual partner's fantasies chime exactly with his own.

Every known civilisation has included prostitutes. Sometimes they have developed a refined and exquisite way of life, as in Japan, but whatever cultural form they took, prostitutes have been a fact of life for many men, who have usually tried to shield women from knowing about these activities. Nowadays that is not easy, when no area of life is taboo and the darkest corners of human behaviour are examined under the blinding light of the media.

It is a light that illuminates little and usually sends us crashing into a moral brick wall. Maggie O'Neill, a senior sociologist at Staffordshire University, says: "The law is drenched in Victorian morality. Victorian ideas of social purity and morality still dominate in this area."

And so there we are, trapped with an increasingly intrusive media which constantly excites in us an anachronistic morality that only entrenches the problem still further. Better that there should be discretion and privacy or civilised openness, but not this mess in between.

Ms O'Neill has been collecting information on prostitutes since 1993. She believes that about one man in 10 visits a prostitute, though it is difficult to establish how often. The men are not hapless victims. Sometimes they are pillars of society who have preached about moral values and so are judged to deserve to fall for their hypocrisy. The hypocrisy is a vital part of the thrill: what is the point of doing something that is condoned when you can get a thrill from doing something furtive and forbidden? "There is a thrill in the danger, particularly in using street prostitutes. They enjoy the window-shopping aspect of it: driving around, selecting a girl, making a purchase. The actual encounter itself lasts barely seven minutes," says Ms O'Neill.

How can seven minutes of a man's life be allowed to ruin him? It must be because we thrill to the chase, the hunting down and naming of the man involved, with little thought to what that says about the moral climate we condone in taking our passing pleasure at the destruction of respectability.

To return to Kundera, the curtain between the public and the private is increasingly threadbare and tattered. It is a commonplace in the wake of Margaret Thatcher's privatisations to argue that as a society we are becoming more privatised; but in this area of sex and morality, privacy and choice are increasingly under threat from the prying prurience and moral hysteria of the media. We desperately need to restore the sanctity of the private. Kundera's curtain needs to be put back.