By the time it ends next September at Wembley Stadium, 15 months after it began in Brixton, Coldplay’s Viva La Vida tour will have played 108 dates and taken them to 17 countries. They will have sold well over one million tickets and confirmed themselves as earth’s most popular group until U2 are back.

Last night they returned to the city where they formed, staked their claim for greatness and emerged triumphant. Surely nobody can doubt them now. In truth, we shouldn’t be surprised. Singer, guitarist and pianist Chris Martin’s outer geek has always obscured his inner take-no-prisoners ambition.

That geek momentarily re-surfaced when he anointed London as “the best crowd in the world” (I bet he says that to all the cities) and instigated a left-side, right-side cheering competition Westlife might spurn on naffness grounds. He just can’t help himself —and Coldplay still dress like farmers.

No matter. As Martin’s actress wife Gwyneth Paltrow bobbed merrily among the masses, albeit with her own security, Coldplay were everything you could hope for from a world-bestriding act (apart from a savagely truncated Talk) and much more.

There were big songs, played in a big arena for a big audience. Viva La Vida itself (further proof that timpani are always a good thing), Clocks and Speed Of Sound were windswept, fist-shaking epics, delivered at breakneck speed, skull-spinning volume and with genuine gravitas.

Yet — and this is the key to Coldplay — just as they can crank it up, they can take it down. The hymnal Fix You, the percussive Lost! and Yellow, during which giant yellow balls fell into the crowd, were intimate and desperately moving.

After Lost! the foursome hurtled through the startled crowd to some cheap seats near the back where they were joined by actor Simon Pegg (who had cast Chris Martin in Shaun Of The Dead and is godfather to Apple Martin) on both the acoustic Green Eyes and drummer Will Champion’s vocal showcase Death Will Never Conquer. Before you could say “brilliant idea, brilliantly executed”, they had sprinted off again.

There was even room for alluring strangeness in the multi-layered, tempo-changing 42; a glimpse into how the world might sound if Stockhausen had sold more records than Stock Aitken Waterman. Just when you thought things couldn’t get any more swaggeringly surreal, they cheekily covered Take That’s Back For Good.

Brave, challenging and fiercely entertaining, pop music as it ought to be.

Coldplay play the O2 Arena tonight and tomorrow. Sold out