Around 150,000 fans braved the unseasonally cold weather to see the aging rockers, and the organizers are confident another 120 million around the world will tune in soon to see the concert on television.

The Guardian newspaper said the event was "the middle-aged rock lover's wildest dream come true -- an all-day event with a line-up so stellar that Bob Dylan is only a support act."

"Bob probably hasn't been third on the bill since he was scuffling around Greenwich Village (in New York) in the 1960s," it added.

With Rolling Stone Ron Wood on guitar, Dylan played a rocking set leavened by an acoustic version of the rambling "Tangled Up in Blue," leaving to polite applause.

The Who reformed for the event to stage what was described as the "live debut" of their Quadrophenia album, already turned into a feature film in 1980. A film backdrop and star guests from the media and music world helped tell the story of Jimmy, struggling to come to terms with life amongst the Mods, the 1960s youth movement that claimed The Who as its own.

Zak Starkey, son of Beatle Ringo Starr, played drums. He was given his first drumkit by the Who's original drummer, Keith Moon, one of rock's famous drug casualties. Guitarist Pete Townshend has poor hearing, thanks to all the over-amplified gigs he has played over the years, and singer Roger Daltrey wore an eye-patch after Gary Glitter clobbered him with a microphone stand during a rehearsal Friday.

The 51-year-old Townshend refrained from the guitar-smashing that used to be his trademark, but the performance received a rapturous ovation.

Top-of-the-bill Eric Clapton started on acoustic guitar with perhaps his most famous song, Layla, and followed with a mixture of crowd favorites and old blues songs.

Clapton has been here before, in 1969, when his short-lived group Blind Faith made its debut in Hyde Park.

The other star of the event, Canadian Alanis Morisette, 22, was not even born then, but she earned her place on the bill thanks to the success of her album "Jagged Little Pill," a million-seller on both sides of the Atlantic.

The concerts of the 1960s and 1970s were free, often chaotic events, and anti-establishment lyrics were mandatory.

In contrast, Saturday's concert was sponsored by a credit card company, Mastercard, and raised money for a royal charity.

The fans had to fork out $12.50 for their music and were penned inside six miles of fencing. Alcohol was barred. Some $1 million was raised for Prince Charles's Prince's Trust, which helps young unemployed people.

The heir to the throne, who is known not to share his estranged wife Diana's love of pop music, stopped by to click his fingers to The Who and told Dylan backstage it was a shame he had missed his set.

Up to 150,000 music lovers converged on the park to see performances by such legendary names as Bob Dylan, Eric Clapton and The Who's Pete Townshend and Roger Daltrey, as well as the 1970s' glam-rock star Gary Glitter.

Young "mods" on their scooters, attracted by the first live performance of The Who's Quadrophenia rock opera, mixed with grandfathers as rock rolled back the years in aid of the Prince's Trust charity. Organisers expected the Mas ters of Music concert to raise £500,000 for a variety of the trust's charitable projects. Prince Charles, Mick Jagger and Billy Connolly were among the audience.

The massive concert was opened by a band of eight young unemployed musicians from the charity's rock schools with a selection of well-known songs. "It was breathtaking, amazing, just overwhelming," said Olive Thomas, 25, a backing singer from Leamington Spa. "Before that all I'd done was a couple of karaoke nights in a pub when there were about 100 people listening."

The Who regrouped to give their first live stage performance since the 1980s. Critics have suggested they are a little old to be hurling themselves around a stage: over-enthusiastic preparations led to Daltrey, the lead singer, receiving a black eye after being accidentally hit by a microphone swung by Glitter during rehearsals on Friday. An eye patch with the old mod target marking covered Daltrey's eye yesterday.

Younger fans who could not remember the days of mods and rockers were treated to a performance by Alanis Morrisette, a 21-year-old Canadian star who has achieved a cult following and huge record sales in the past two years. For others, how ever, the biggest draw was Dylan, performing for the first time in Hyde Park. Alec Sutherland, 57, a community care manager with Help the Aged, who had travelled from Manchester with his wife Joyce, 54, and son Simon, 22, said: "I just think he has been the major influence on rock music."

Dylan, however, apparently forgot the words to the song Seven Days, according to Ron Wood, the Rolling Stone who was his backing guitarist. "He came to me and said, 'How does the last verse go?'," said Wood. "I said 'I don't know, you wrote the song', and then he said, 'Give me a clue'."

Meanwhile, at the Old Trafford football ground in Manchester, 60,000 people rocked in the rain to a younger generation of super groups, including Simply Red and M People. At both concerts every rock cliché, down to lit matches held aloft, was honoured.

For some, however, it was all a far cry from the rock festivals of the Swinging Sixties. Alcohol was banned from Hyde Park, as it is in all royal parks, and the event was sponsored by Mastercard.

Festivals have come to something in this country when they have a credit card company for a sponsor and when you cannot get a beer," said Andy Kershaw, the rock critic. "It lacks that festival fragrance of English beer spilt on crushed grass."