'A turmoil of writhing bodies'

The girl with the cut-glass accent was becoming more persistent in her attempts on my zipper. Across the room Harriet, my partner for the evening, was fending off a man looming over her with lustful intent. On the floor three men were having sex with a blonde girl who had just been telling us, rather charmingly, about her recent holiday in the Caribbean.

And, in a corner, a man in a pin-striped suit joined the queue for the attentions of a woman in black lace lingerie.

Thus, in night-time London within a stone's throw of the British Museum and the Royal Opera House, the chattering classes indulge in their latest opiate - somewhat coyly known as "couples' clubs".

In plain language, the purpose of these clubs is to have sex with strangers. They are lawyers, doctors and stockbrokers; people who make society work.

Yet, unseen and unsuspected, they are part of the growing phenomenon that was once called swinging.

Now, in this most recent chapter in the sexual revolution, these individuals style themselves as "players".

Evening Standard writer Harriet Arkell and I posed as a couple who were curious about the group sex scene. We joined the Toucan Club, one of the first of a growing number of internet-based organisations that host sex parties.

Joint membership cost £50, including admission on our first visit. Secrecy surrounded the party venue, and we were told we would not be given the address until the day it was held.

Then, a few hours before the party started, we were told to go to Corts wine bar on High Holborn. The bar had been hired for the evening and by midnight around 50 couples had arrived.

It began with a glass of wine, a sociable chat, a dance. It ended in an astonishing erotic free-for-all.

At street level theatregoers were making their way home and cabs were dropping off guests at the five-star hotel opposite.

But, in the basement, a scene redolent of ancient Rome was unfolding. And this was merely a snapshot of something that is happening elsewhere in London and, indeed, in other parts of Britain.

Couples' clubs are everywhere. They are based around suburban drawing rooms, hotel suites and rented bars.

The current axe murder trial in Yorkshire has heard evidence of depravity, with courtroom stories of fetishism and sex in car parks.

But this is a world away from the highly private and exclusive clubs that have begun to proliferate in the suburbs and the shires. One, based in London, refuses to admit members who are over 40 and each person is rigorously vetted for looks and social credentials.

Our odyssey through the barely-charted waters of the group-sex scene uncovered a social sub-strata of couples who hold down responsible jobs, who build homes, who raise families, yet have a secret world in which they do things most people would find abominable.

It raises a perplexing question - what is it that drives intelligent, attractive people to crave orgiastic sex?

The evidence is that recreational group sex is attracting more and more couples, inevitably prompting concerns about what this may be saying about the way society is moving.

Or is it merely the inexorable march of the sexual revolution that continues to sweep aside the last remaining taboos? The search for an answer led, ultimately to the amazing scenes in the Holborn basement.

But first there was much to be learned. The crucial element in the astonishing growth of couples' clubs is the internet. The days of contact magazines and plain brown envelopes are fading fast. And, as the Web takes over, a new and more sophisticated generation is drawn in.

People like Katie. She is a politics, philosophy and economics graduate who recently set up her own internet website for couples who want to play.

She is 30, an affluent professional in a long-term relationship with Ken, whom she met at university.

They are the new face of swinging. They live in Essex and lead what they say are "normal" lives in every respect except one: they choose sexual partners from the 2,000 people who they say have joined their internet-based club. Katie said: "Swinging is an old-hat term but we use it on our local swingers website because it's something people recognise. We wanted to meet people who enjoy doing the same things as us.

"It started at university when a friend of mine kept asking me to do sex with her. I finally agreed, as long as Ken could join in. It was fantastic.

"We lost touch with her but we wanted to find others. We went through the usual business of agencies and contact magazines but, frankly, it was all very lowrent and not us. We didn't want hardcore porn or people sending us dirty messages or pictures. So we set up the website.

"It is the perfect medium. People can tell us about themselves, download photographs, make arrangements to meet - all very discreetly.

"We met this couple for drinks, hit it off and now we're in a scene with them. It's brilliant.

"A lot of people will find it odd, because I'm not bisexual and my preference is definitely male.

"But we just like to have sex with other people."

So, clearly, do many others. It is impossible to know precisely how many people are involved but a dozen or so leading clubs claim thousands of members each. One is Samantha's, run from a Victorian country house in Shropshire. Parties are held in the main house and there are rooms in a coach house and converted stables.

A club organiser said: "We have parties for swingers on two Fridays a month. They are extremely well-attended. We find that two couples will often want to get together with one other person, usually a man. So we invite single men, but only those who have been checked for height, weight and their waist measurement.

"We are not keen on short, fat men. They have to be attractive." Looks are also a priority for a group called Fever, which holds parties in London and the South-East throughout the year. The next is in Brighton in June.

The Fever people are young professionals who operate through a slick website. Would-be partygoers have to submit photographs and details about themselves to a committee, which then decides whether they will receive an invitation. Half are turned down.

The Fever organisers have a strict rule that no one over 40 is allowed into their parties, and they stress they want only young and good-looking couples. For those who are successful, "breathtaking" sex is promised.

Like most couples' clubs, Fever says it is non-profit-making and run solely for its partygoers. The charges suggest this is probably true.

Couples who are successful in receiving an invitation are asked for a £45 "contribution". This covers the cost of hiring the venue, which at next month's party includes a swimming pool. Fever likes to think of itself in terms of glamour - a quality not always associated with such activities.

Some couples' clubs are positively quaint, though. One, based in London, organises gourmet dinner parties for couples who want to have sex with other guests after the coffee.

This club, Rude Food, is run by a middle-aged couple, Jeff and Cathy. For them, a perfect evening begins with intelligent conversation over a finely-prepared meal and good wine. Then dinner guests are invited to undress and have sex with each other. Jeff and Cathy advise: "Please leave your inhibitions at home."

In fact, the playing scene has its own strict etiquette. Bi-sexual women are encouraged; homosexual men are not welcomed. Party organisers say they are constantly trying to keep out men who hire a prostitute to create the illusion of a couple.

And, as if to underline the middle-classes' growing preoccupation with sex with strangers, the hosts of parties held at a country house in Berkshire warn guests: "Don't bring cheap wine."

But the most important rule is always secrecy. Cameras are never allowed and the vetting of partygoers is strict. Many clubs demand home addresses and names that can be checked against the electoral roll. Among partygoers, first names only are used.

Discretion, security and trust are all important words in the swinging lexicon. But what of love? Can it really be possible for a couple who love each other to routinely pair off with strangers? Certainly, it can lead to problems between couples and the breakdown of relationships.

Denise Knowles, a psycho-sexual therapist who works with the counselling charity Relate, said she is consulted by a large number of people who want advice because swinging is threatening their relationship.

She said: "We see more and more people in their twenties who are going in for this kind of activity. Often the problems start when one partner decides they have had enough of it but the other wants to carry on. You then get a situation where one person feels under duress. This is not always the woman. Men might try it, then decide it's not for them but the woman has become hooked. That can be very difficult.

"Swingers sometimes say that their relationship is strengthened by having the freedom to experiment and share.

"They say they never get bored with their own partner and infidelity is never an issue. But the reality in many cases is that they are simply emotionally immature.

"They want the stability of a home and family but they also want the thrill of an adolescent lifestyle."

But nothing says so much about the strange world of swingers as the parties themselves.

Founded by committed swingers Phil and Sarah, the Toucan Club has a reputation in this bizarre milieu for organising some of the best parties. They start at the ground-floor bar, where an acceptable house white costs £13.50 a bottle - although several couples chose champagne.

They gathered in groups, chatted, laughed and sipped drinks. As each new couple came in they were discreetly appraised by people at the bar. Some of the women wore revealing outfits; some of the men wore suits and a few looked as if they had come straight from the office.

Clare, a thirty-something redhead who said she was a writer ("Don't worry! Not newspapers"), instantly identified us as "first timers" and gave us a briefing.

She said: "No one's going to rip your clothes off, and, if you don't want to do anything but look, that's fine. But you will probably find you want to get involved.

"I started going to these parties four years ago and was nervous at first. But, after a couple of drinks, I wanted to join in too."

She continued: "Once I was at a house party in the country, and there were 25 blokes and just three of us girls."

Clare said the party would not really start until people gathered in the dimly-lit basement.

She was right. Slowly, people began moving downstairs. The room was arranged like a discotheque, with armchairs and sofas around the walls.

We fell into conversation with Julian and Sophie. He said he was in the property business, although he had the magisterial bearing and the carefully modulated voice of a judge. He said he had a wife and grown-up family, and homes in Kensington and Wiltshire.

Sophie, with whom he had had a clandestine relationship for a number of years, was a highly attractive and immaculately dressed woman who appeared to be in her late thirties. She said she ran her own company.

Julian was quite open about wanting group sex and made it clear he envisaged a partner swap. Sophie suggested a private lunch at Nobu to discuss a further encounter.

"It's so nice to meet people like us," Sophie said. "Julian found out about this club while he was surfing the internet in his office and, although we'd been assured we'd meet nice middle-class people, you never really know, do you?

"But everyone here seems to be well-spoken and well-educated."

As we chatted a couple nearby began to have sex.

This seemed to trigger a chain reaction around the room. Suddenly, couples and small groups became engrossed in each other. In a corner a woman in black lace underwear was performing a sex act on a man as other men waited in a queue behind him; two women were cavorting together on a chair; at least three women were entertaining several partners at once.

The rest, for the most part, watched. I spotted an executive from the Telegraph newspaper group among these voyeurs. A couple who had kept to themselves all evening suddenly began to have sex with each other, all the while looking around to see who was watching.

When it was over they slipped away. This reinforced what was already a powerful sense of the surreal.

Curiously, perhaps, no one undressed. Women merely hitched up their skirts and the men remained fully clothed. A man in a pinstripe suit didn't even loosen his tie. The room was a turmoil of heaving bodies, it was impossible to discern who was doing what to whom. I caught Harriet's eye and she nodded.

It was time to make our excuses.