Coldplay, Earls Court, London <!-- none onestar threestar fourstar fivestar -->

Coldplay could be accused of striking down a generation of British rock music. Embrace, Athlete, Keane, even Jamie Cullum, are their children. Where Chris Martin started the dilution of Thom Yorke's genuinely agonised howl into a bleat of polite distress, these others have followed. It has diverted bands who are supposedly part of the rock tradition straight into the middle of the road.

In the process, Martin has become a major rock star, while his band affect EMI share prices as the Beatles once did. His unworldly, earnest attitude is a far cry from previous, anarchic generations. It is summed up by the big hit from Coldplay's new album, X&Y, "Fix You": a palliative for people who aren't really broken - just slightly sad.

The whole album is equally vapid. Initially intended as a Kid A-style great sonic leap forward, Martin soon gave up on that. So crucial are his band to magazines' bank balances as well as record companies', though, that it has passed as some kind of classic. It's not Coldplay's fault - they're an honest band. But they've been disastrous for music.

The support act, Richard Ashcroft, who, with The Verve, joined Radiohead in creating a far more passionate, extreme version of the sound Coldplay have cribbed, might be expected to act as a corrective. A stringless "Bittersweet Symphony", though, suggests he has lost his way, too.

When Coldplay do appear, there's little to distract visually from their music. Instead, the huge crowd have to make do, mostly, with watching the four distant, life-size people behind all this sensation. "Yellow", the limpid ballad that made their name, is tossed away early, a sure sign of perceived strength. Though not to everyone's taste, it is the hardest thing in pop, a natural hit, one of half a dozen they've manufactured to date. "Speed of Sound", an X&Y single built on a slick, Kraftwerk-style bass riff, proves their variety and skill. Both songs cause mass embracing, the same communal experience Oasis once gave. Before long, Martin, briefly alone at the piano, casually leaves spaces for the crowd to sing for him, knowing that they will.

There are moments that come close to the strange, raw beauty of folk music. Acoustic guitars and harmonicas pierce the air, as a Johnny Cash tribute is followed by Cash's far superior "Ring of Fire". If the elemental ferocity such music requires is beyond Coldplay, at least they try.

"Clocks" reveals they are U2-lite, as the singer essays a Bono-like scream of supposed transcendence. As the beat rattles into overdrive, we finally arrive at rock'n'roll.

For "Talk", there's a moment of dark near-mystery, as screens show Martin pleading: "I'm so scared about the future - and I don't know what to do." The encore "Swallowed in the Sea" is genuinely, ambivalently epic - a late glimpse of why they're loved.

For tour dates, see www.coldplay.com