There's discord in the world of music, and it's emitting from an unexpected source. The normally placid Julian Lloyd Webber tells Anna Tims that new musicians are destroying the classical tradition, and he is determined to restore harmony in every sense.

Julian Lloyd Webber is an unexpected revolutionary. The 46-year- old cellist, noted in the music world for his mild-mannered charm, comes carefully into his living room bearing a plate of biscuits and a voluminous cat. Around and above him are framed LPs of Elgar, Shostokovich and Buddy Holly and, lining the walls, pictures of him posed dotingly with his infant son.

Yet Lloyd Webber is quietly preparing for warfare, his weapon a speech he is delivering in Switzerland today which is intended to inflame the music world. His grievance is one long shared by the majority of concert- goers: that five decades of "clashing lawnmower" music have all but destroyed the classical tradition in the West. "I've nothing against atonal composers," he says. "I'm sure there are people who like that kind of music. What I object to is the unspoken dictatorship that permitted only one style of music. Composers who pursued a logical development of the music of the great masters were derided by the new fuhrers of the establishment for whom tonality and harmony had become dirty words. And I'm the first musician to speak out against it."

It is an extraordinary admission from a musical "insider" and will come as a relief to those who have struggled baffled through a performance of Stockhausen or Birtwistle. Even more extraordinary is the fact that it has come from Julian Lloyd Webber, a man so unassuming he is wary of granting interviews lest it appear he is self-publicising. So what made him finally speak out? "I was asked to give a speech at the World Economic Forum in Davos on a subject of my choice," he says. "Musicians have been talking about the problem to each other a lot, but I feel we have to stand up and be counted. Discussion is one of the first steps to a solution and the truth has to be faced before it is too late: the vast majority of young people in the West have no interest in classical music whatsoever."

Norman Lebrecht in his doom-laden prognosis "When the Music Stops" dates the decline of classical music from the first Three Tenors concert in 1990. Lloyd Webber reckons the rot had set in long before that in what he calls "forty years of madness" - from 1945 to the early Eighties.

Immediately after the war there was an insatiable thirst for novelty as the battered nations of western Europe tried to reinvent themselves. In London, plans to rebuild the beautiful, bombed Queen's Hall were shelved in favour of a new, concrete and acoustically inferior arts centre south of the river. "All over the West, grey mausoleums were becoming synonymous with classical music," says Lloyd Webber. "And as the concert halls became more severe, so did the music itself. Suddenly it became acceptable to write in only one style and classical music created a pernicious politburo which proved every bit as effective as its counterpart in the East."

One of the best-known doyens of dissonance, Harrison Birtwistle, recently dismissed accusations that his music was uncompromising by declaring audiences should come to him rather than the other way around. It's an attitude that infuriates Lloyd Webber. "If people want to write like that it's up to them but they can't expect many to come and hear them. We've always been happy to tell audiences they don't like it because it's beyond them and that's not on. In the Seventies when audiences were becoming alienated by contemporary composers, people said, give it time - Debussy and Prokofiev had bad reviews at first. But the truth is, musicians believed in Debussy and Prokofiev's music and it only took 15 years for audiences to come round to it. Now people never will. We as musicians have broken faith with our audiences."

These comments will inevitably provoke fury from die-hard radicalists, but then Julian Lloyd Webber is no conservative. His recording of Benjamin Britten's notoriously challenging cello concerto was described by Gramophone magazine as "beyond any rival", and he has spent the last 10 years commissioning new works in order to widen the cello repertoire.

The climate, he says, is changing with a new generation of composers returning to more "audience friendly" styles. There is also new interest in composers whose melodic works were dismissed as dated in the Fifties and Sixties. However, recognition has come too late for Lloyd Webber's father William. It was William who inspired Julian and his brother Andrew Lloyd Webber to pursue musical careers, but although he was a talented composer he abandoned his music in the Fifties at the age of 38. "His spirit was crushed by the intolerant attitude towards any music with harmony," says Lloyd Webber.

Ironically, Andrew Lloyd Webber has been hailed by some as the late 20th century's answer to classical music for precisely the qualities that scuppered his father's career, but Julian Lloyd Webber refutes claims that his brother is the next Puccini.

"Andrew's music is very eclectic and I don't think he'd say that it has grown out of the mainstream of classical tradition."

Lloyd Webber is convinced that there is a far larger potential audience for classical music than is generally supposed. What worries him is that the new breed of tonal composers such as James MacMillan, Gavin Bryars and Michael Nyman are finding it that much harder to make their mark because of public mistrust of modern music.

"Attitudes are shifting," he says. "I recently performed a new concerto by Gavin Bryars who, 20 years ago, would have been completely dismissed. The trouble is the media is not letting people know. A new Shostokovich or Prokofiev symphony travelled the world very quickly with a large public waiting every note. Now it will take any new masterwork considerably longer to be recognised for what it is."

A knock on effect is that fewer children are taking up musical instruments. In time, Lloyd Webber predicts, classical music will be dominated by the Far East. "The gap is closing between Western and Eastern orchestras," he says. "In Tokyo there are seven orchestras, most of them on a par with their Western counterparts, whereas here young people are force-fed their culture by the media and that culture is pop, pop and more pop."

Lloyd Webber is now issuing a challenge to the breakfast television programmes. "Give me four weeks of daily three-minute slots and I will deliver you 20 young musicians who will captivate your viewers," he says.

In the meantime, he is sufficiently optimistic about the changing climate to attempt a composition of his own. "Maybe it's because you no longer have to pretend to be something you're not. It's not that I and my colleagues are looking for some bland, user-friendly piece to play; there will always be a time when music is challenging like Britten's cello concerto. But it has to be worth it. And frankly I don't think a lot of what's been produced over the last 50 years is."