This was the Mistletoe Ball, held at the Equinox club in Leicester Square, an exclusive party for 13 to 17-year-olds, creamed from 148 public schools, drawn from the blue bloods and mega-rich, from the families of Windsor, Lichfield, Balfour, Kashoggi, Keswick and Rothschild.
These darling buds had queued for up to an hour, their anxious fathers patrolling the crocodile, fending off leering drunks and over-inquisitive tourists, offering the same plaintive refrain: "What can I do? Her peers are all here. I can't lock her up."
Parents had placed their trust in a boy barely older than their own children. Justin Etzin is 19, an ex-pupil of Bedales and the son of a millionaire. He lists his heroes as Richard Branson (inevitably) and (less predictably) Frederick Barclay, of the Barclay twins, owners of the Ritz hotel. Frederick, he says, gave him his best piece of advice: you never make money lying in bed.
Staging these balls for the children of the elite, at pounds 20 a head, is making Etzin a very rich teenager. This year, his company, VIP Promotions, will stage nine similar events, including a Valentine's Ball, at top London nightclubs. He and a handful of competitors are exploiting a niche market. They sell the balls to parents by guaranteeing no drugs, no alcohol, no aggro and constant supervision - and to the children they sell the promise of no parents.
There is a precedent in the Gatecrasher Balls of the mid-Eighties. "Unbridled lust among upper-class Lolitas and public school Lotharios," screamed the Sunday Telegraph at the time. Gatecrasher was a company run by two teenage entrepreneurs, Jeremy Taylor and Eddie Davenport, the sons of landed gentry and a Chelsea restaurateur, who tapped into the frustrations of children at single-sex boarding schools. What public school pupils wanted most, they decided, were parties for meeting the opposite sex. Soon, they were raking in pounds 250,000 a year, until stories grew of adolescents swigging alcohol and grappling under tables. Davenport, a member of the well-known brewing family, narrowly avoided a nine-month prison sentence for VAT evasion.
Peter York, the social commentator and co-author of the Sloane Rangers Handbook, remembers Gatecrashers as a combination of the warehouse parties of Steve Strange and the traditional "taffeta" balls. "They were an instant rave for Sloane Rangers, but with a real kind of car dealers feel to them. It's a good money-spinner, a way to make a fast buck. It's having all the technology and ideology of raves, but, each time you read about it, it's presented as a posh ball, sending a signal to certain types of parents and their children. It just goes to show that the aspirations of the Sloane Ranger days are not dead. There are still kids who want to be with their own kind."
Etzin is at pains to avoid comparisons. "The children are safer here than at a private house party," he insists, "and better supervised. We're not trendy enough to attract the really wild crowd, nor do we want to. We have bouncy castles, for goodness sake. The real trendy teenagers, or the ones who think they're trendy because they take Es and drink or whatever, wouldn't be seen dead here."
At 5pm, four hours before the doors open, Justin Etzin arrives at the Equinox. The place is empty but for cleaning staff sweeping away cigarette butts and discarded plastic cups from an office party the previous night. The PA plays the cleaners' choice: hit songs from the musical Grease.
Etzin, dark-haired and gangly, in a camel hair coat and Levi's, is pacing the dancefloor. In between checking the sound system and planning where to put the gunge machine, he briefs his team - five full-time employees and 30 on contract. They have to search everyone, no matter who their father is, for drugs, alcohol and cameras. He's also just heard from Scotland Yard that the prince will be attending - the second time William has been allowed to go to one of Etzin's balls - and someone has tipped off the press, which is why teams of tabloid hacks are lurking.
To make up for the total ban on cameras, Etzin has employed an official photographer, a slightly seedy-looking middle-aged man. Etzin has also drafted in members of his family. His mother, Judith, is staffing reception, dealing with gatecrashers and late-ticket purchases, and his 17-year-old sister, Danielle, together with several of her friends, are body-searching the girls. This takes a good hour. But teenagers can still get tanked up before they arrive. A paramedic unit stands by.
Judith Etzin, cool and slightly haughty, is talking to a tearful 13-year-old who says she has paid for her ticket but left it with friends. The telephone number she gives does not exist. Mrs Etzin tactfully coaxes her address out of her. Then she's approached by a particularly snooty boy of about 14 who has mistaken her for a ticket girl. "Could you look after my umbrella, but make sure I get it back," he commands. When she directs him to the cloakroom, he impatiently thrusts an ordinary black brolly across the desk. "Oh, keep it!" he cries at last, "it only cost me pounds 2, anyway."
Outside, homeless people who have spied rich pickings are being moved by police to adjacent doorways, where every so often they plead for loose change. Inside, Etzin is growing more frantic by the hour. A former colleague, now a rival, turns up. Ajit Vyas, the son of a wealthy Indian family, starts handing out flysheets. The two of them have a stand-up row.
Prince William has already arrived through a side-entrance, starting a royal rumour machine. By the end of the night, people are convinced they have seen him snogging, reeling around drunk and leaping on the bouncy castle. In fact, he sticks quietly to his group and leaves before 11pm.
I notice four prowling adolescents from Bacon College in Rotherhithe, conspicuous by their lack of plummy accents. "We get free tickets because my mate's dad is a bouncer at another club," explains one. "When we came to our first posh ball, we just couldn't believe it. These upper-class girls are so easy. They will let you go as far as you want, provided the bouncers don't catch you. Not like the girls at home."
By now, more couples have paired off. I try and talk to a weedy 14-year-old who has come up for breath. "Give us a snog, darling, and I'll tell you anything," he sneers, waggling his tongue. To his left, two teenagers are sprawled across one another. The girl's skirt is up, and the boy is kissing one breast. Another girl sits astride a boy, rotating her hips. They have to be prised apart by a minder.
I find Etzin in a private bar, throwing a VIP champagne bash for close friends such as David Rothschild, the 19-year-old son of Sir Evelyn. In view of what I've seen, I ask him if the upper and upper-middle classes are less inhibited than other adolescents. "A teenager is a teenager," says Etzin. "Whether they come from a wealthy background or not, they have the same urges. But children who go to boarding schools probably are less inhibited because they do not get to see the opposite sex on a daily basis. They don't have the time to wait around. They kind of need to get on with it."
Getting on with it is Etzin's speciality. His precocity was evident as early as six. His mother, a former actress born in Australia, recalls that, at an age when other children were playing post offices, he was pretending he owned Harrods.
"He'd take household items, ornaments, things which he perceived to be of value, and set them up on a table," she says. "Each time we passed, we'd have to buy them back. His schoolteachers used to joke about him needing a personal secretary. We never pressured him, but I think his business talent is inherited from his father."
Justin's father is Bernard Etzin, a multi-millionaire who develops hotels. The family own a four-bedroomed flat in Knightsbridge, a mountain retreat in Cap d'Antibes, and an exclusive resort in the Seychelles (where Justin spent Christmas).
Bernard Etzin's story is itself remarkable. Born in Japan in 1930, the son of a silk exporter from Lithuanian, he became, at the age of 15, part of the American army's advance team in Hiroshima, ten days after the atomic bomb had been dropped on the city. He worked both as an interpreter and personal assistant to General Eisenhower. When he was 17, he arrived in New York with, he says, only $1.10 in his pocket. With three Japanese brothers named Yasui, he set up a company making sewing machines. Today, the Brother International Corporation (which he has since left) is an empire selling a variety of goods in 150 countries.
Until Justin was six, the Etzins lived in Hong Kong, with a cook, cleaner and chauffeur. Justin claims his parents always stressed the good fortune of his upbringing: "I dressed myself and tidied my own room, when I could have just sat about like a little prince. My parents always reminded me of what I had to lose. I have never wanted my father's money because, when money comes too easily, it can go just as easily. I don't think you can take it for granted that your parents are always going to be there with their money to pick up the pieces. My parents could make a mistake and their money could disappear. So I work for myself - and I work very hard."
Justin was 12, and living in Knightsbridge, when he started his first business, car washing, targeting customers of Harrods and other local stores who parked on meters close to his house. He bought three T-shirts and had justin's carwash printed on the front; then he employed friends at 50 pence an hour.
"We charged pounds 4 for cleaning, inside and out. We got to wash our dream cars, Ferraris and Jaguars - it was amazing. I was making pounds 80 a week at one point. Then I gave my friends a rise. I didn't make them partners because, after all, it had been my idea." His mother would ask when he was going out to do something normal, like play football. "I'd say, on Sunday, when Harrods is closed."
At 13, he opened a market stall on the King's Road, selling trivia such as pop posters and water-operated watches, which he ran at weekends when home from Bedales. Again, he got his ideas from visiting Harrods: "I'd go in and ask the assistants which novelty product was selling well, then go away and order a batch from the manufacturer, so I was undercutting Harrods."
Tash Archdale, the 19-year-old niece of Sir Edward Archdale (whose recreation in Who's Who is listed as "Civilisation"), is breathless in admiration of her old schoolfriend. "Justin is amazing," she rhapsodises. "I met him at the Bedales entrance exam, and ever since I've known him he has always been thinking up new ways to make money, going after the deals. Girls my age think he's a super catch."
Tash is greatly tickled by what she describes as "Justin's scams" - she says he gets free membership of health clubs by saying he's Lord Etzin. "When a group of us were on holiday in France, we got on to people's yachts by pretending we knew them when we didn't. There was even a time when he was going to sell very cheap Levi's to all of us at school and make his fortune that way." The jeans turned out to be copies, and the deal fell through.
Etzin's first party promotion was five years ago, when he was 14. A disaster. "I asked a friend who had a shop on the King's Road if we could have a party in his basement. Then I printed flysheets and handed them out from my market stall. On the night of the party, the police boarded up my friend's shop. They must have thought I was planning an illegal rave. I wasn't - it was just naivete. I didn't know about entertainment licences and that sort of thing."
But at 16, he cracked it. A ball he staged at the Ministry of Sound in London proved a roaring success. He had hit on distributing his publicity through friends at major public schools. Now he has 8,000 customers, most of them children from internationally wealthy families, which he keeps on a confidential database.
He claims that, at least on paper, he's a millionaire; he goes to the Paris fashion shows, he wears Gucci and Versace. Not bad for a 19-year- old with pimples. He has a two-bedroomed flat in Chelsea. He had a Mercedes, too, until he wrote it off. But he has a problem: Ajit Vyas. According to Vyas, he and Etzin staged parties together for two years. They fell out last April, and now Vyas, 23, runs another company, called Social Life.
Vyas claims that Etzin's mother is really the driving force: "She does a lot of pushing - in the beginning, she practically organised the parties. Then they decided they could do it alone. Justin just started making arrangements without me. Now he's got all the publicity because Prince William went to two of his parties." He paused for effect. "Actually," he added, " William might be coming to one of mine in February."
At 2am, going-home time, Justin Etzin stands in the foyer as final kisses are snatched and girls with mascara streaks adjust their sweaty clothing. As they queue for their jackets, boys and girls lean against one another, utterly exhausted, like small zombies; then emerge, blinking, to the embrace of mothers and fathers, who have formed a crowd in Leicester Square. "Darling, was it lovely?" they are asked; and then the little blessings are whisked away.
First thing next day, Etzin is back in his office. He works from a small, rather messy room above a shop on the Fulham Road, where he serves me coffee in chipped mugs. "Excuse the office - we hope to move soon to Chelsea Harbour," he explains airily. Phones ring incessantly. The parents, I am given to understand, are busy booking up for his next event.
There are also persistent telephone calls from someone who, from the tone of the conversation, could be another journalist. This time Etzin is not so charming. "Look, Clive," he says, "I cannot talk now. I'll come over. Can you send a car?"
I look around his office, bored with waiting. On his noticeboard is a vaguely familiar name: Clive Goodman. Etzin comes off the telephone and concludes our interview. He has to dash. Who is Clive, I ask? "I'll tell you later," he snaps.
The following Sunday, the front page lead of the News of the World screams royal sex orgy shame. I read of how "Wills watched as couples romped!" Pages four and five are given over to photographs of cuddling teenagers. The story appears under the by-line of the Royal Editor. His name? Clive Goodman