Rear Window / Screaming Teens: We love you John, Paul, George and Howard

THIRTY years ago this month the Heathrow Airport authorities were persuaded, for the first time ever, to keep the roof of the Queen's Building open after dusk. In those days, before the era of international terrorism, visitors could go out on to the roof of what is now Terminal 2 to watch the airliners during the daylight hours. And the events of this particular evening justified an extension.

By half past nine, the roof was thronged with thousands of people, most of them teenage girls - some clutching paper bags full of jelly babies, many waving posters or photographs of four young men with moptop haircuts. From time to time, a chorus of shrill screams fought against the whine of the jets and turboprops. The screams and the photographs made it obvious what was going on. The significance of the jelly babies would emerge later.

At 9.35 the New York flight touched down and taxied up to a special parking space in front of the Queen's Building. A stepladder was wheeled to the aircraft's door. Down it, grinning and waving to the now ecstatic throng on the roof, were the four young men pictured on the posters - the Beatles, returning in triumph from their first full-scale American tour, where they had appeared three times on the Ed Sullivan Show, spoken on the telephone to Elvis Presley, and been paid dollars 150,000 - a new world record - for a single concert at the Municipal Auditorium, Kansas.

It was the end of the opening campaign in what American pop-culture historians came to know as 'the British Invasion': already their records had occupied, simultaneously, the top three places in the US hit parade. Soon they would be followed across the Atlantic and up the charts by Freddie and the Dreamers, Gerry and the Pacemakers, the Dave Clark Five and Herman's Hermits.

In domestic terms, this was a stage in the phenomenon identified a year earlier as 'Beatlemania': the first true expression of the sort of fan worship that has been the proper subject of sociological study ever since, and is again gripping Britain as the Take That tour proceeds around the country to the sound of a hundred thousand screaming girls.

It had its roots in the late Forties, when mobs of bobbysoxers squealed in admiration of the debonair young Frank Sinatra as he stepped up to the microphone in front of the Tommy Dorsey Orchestra in ballrooms around the US. In the early Fifties the squeals turned to screams for the anguished balladeer Johnny Ray, and his hit song 'Cry'. Then the noise took on the sound of full-blooded pubescent sexual longing when Elvis Presley shook his hips to 'Hound Dog' and 'Don't Be Cruel'. In Britain in the late Fifties, while their boyfriends posed in drape jackets and practised their juvenile-delinquent sneers before going off to slash a few cinema seats at screenings of Rock Around the Clock, teenage girls tested the imported techniques of female fan behaviour on such ersatz local rock and roll idols as Cliff Richard, Tommy Steele and Adam Faith.

But it was the Beatles they were waiting for: a quartet of boys who mixed rebellion with Northern wit and softened the edges of American rhythm and blues for a white teenage audience just beginning to identify itself as the core of an unprecedentedly numerous and therefore powerful generation.

John, Paul, George and Ringo: the sharp one, the pretty one, the quiet one (with a taste for jelly babies), the funny one. Something for every taste, packaged in a formula polished and exploited by succeeding objects of worship: the Monkees, the Osmonds, the Jackson Five, the Bay City Rollers, Duran Duran, New Kids on the Block.

After the Beatles, the chief requirement for such groups became a shrewd manager. Brian Epstein may have looked a bit like a rather vague young art dealer, but he laid the foundations on which others built, right up to the latest example, Take That's own Nigel Martin-Smith, whose unthreateningly neat appearance makes him a perfect heir to the tradition.

There's one difference, and nowadays it's a common one. Martin-Smith created the blueprint for the group, cast its members (Gary, Jason, Robbie, Mark and Howard), and controls their lives down to the last detail (no girlfriends allowed; two weeks' holiday a year). The Beatles, on the other hand, invented themselves.

But then again . . . in his book Shout: The True Story of the Beatles, Philip Norman reconstructed the events of the night that Beatlemania was born, when the group played on Sunday Night at the London Palladium and the Daily Mirror cheerfully reported that 'police fought to hold back 1,000 squealing teenagers as the Beatles made their getaway'. In fact, eye-witnesses later admitted to Norman, there were perhaps half a dozen.

(Photographs omitted)