Jamie Cullum, York Barbican Centre, February 27

JAMIE Cullum is everywhere.

Wiltshire's pop face of jazz has been in California, looking to add to the success that has found him outselling the once omnipotent Robbie Williams in the British album charts.

On the day of this interview, he was rushing off to rehearse his performance at the BRITs. "I'm not allowed to tell you what I'll be doing," he says, before having to relinquish the phone in the urgency of meeting his next appointment.

That BRITs contribution turned out to be a decidedly snazzy version of The Cure's The Love Cats with Katie Melua, his fellow breakthrough act of the winter months, who will be following Jamie into the Barbican Centre this season. Both dates, next Friday for Jamie, March 5 for Katie, have sold out.

The momentum is building and building. Last Friday morning, Jamie had awoken to another front cover picture in the newspapers. This time it was a profile of "The Young Pretender" in the Independent's Arts & Books Review, with Cullum pictured in shades and T-shirt against the backdrop of the Hollywood sign, like so many young Brits on their first LA trip.

"Walking into a newsagent and seeing my picture... it's just something I look upon with continuing disbelief," says Jamie.

This may seem ironic, given that the purpose of Universal Jazz's £1 million package for his album Twentysomething must have been to achieve exactly that kind of coverage. Yet beyond the quick-fix world of pop, the British are notorious for throwing such promotion back in its face when they see through the plumage. Not so with Jamie Cullum, who has been greeted as The Young Contender rather than The Young Pretender of the Independent headline.

The 24-year-old former Reading University student has sold 650,000 copies of Twentysome-thing, quite something for a jazz musician. "It helps that I'm a home-grown artist, though I must admit I don't know why I've caught on. I'm just trying to be an honest artist. I think that's what people have noticed," he says.

"Maybe it's also because I can't easily be put into one category. I hope that I'm not just seen as this new jazz sensation. Even when I started to play jazz, I was listening to all kinds of music and working with rock musicians. Hopefully, I'm just being a musician and doing my own thing."

With success comes the whiplash. "People will always make judgements and already you can see a backlash, with people saying 'Why are you not being a rock star instead of doing jazz?', but I think the ultimate rebellion in music is not to be a rock star," Jamie says. "I've been doing this music for quite some time and it's only now that the press is showing any interest."

Jamie made his first album, Heard It Before, while studying film and English literature at Reading, recording it in an afternoon and selling 700 copies at a tenner each. "It really was a wonderful time for me. I didn't really have time to play jazz gigs, perform in plays, make films and study! In fact, I was playing a gig the night before my finals, but I got away with it. I came away with good results."

With the remnants of his student loan and the money made from Heard It Before, Jamie recorded a second album, Pointless Nostalgic, a telling title that indicated he would not be content merely to replicate jazz standards in the manner of a Harry Connick Jr. His jazz cover of Radiohead's High And Dry suggested an inquisitive spirit, and his composition I Wanna Be A Star confirmed an independent streak and a contempt for manufactured pop.

Those first two records were made without pressure, without expectation. Now the stakes are far higher, but he is determined to maintain his progress his way.

"I'm finding my way into that thing of writing songs on tour. I'm starting to find out how to make time to do that, and I'm learning how to cope better with all the different demands on me. I'm already coping better, but sometimes life is one interview after another, and it's difficult to balance everything, especially when you're a solo artist," he says.

The ultimate test, the guide to any chance of longevity beyond mere fads, is whether a musician can cut it on the concert platform, and it is in this arena where Jamie Cullum has always thrived.

"I'll be playing in York with my regular band, a trio with a horn player and a guitarist and me on piano, and having that regular band is absolutely essential to what I do as I never write a set list. So every show is entirely spontaneous, and that keeps it fresh and exciting for us and for the audience," he says. "With jazz, improvising is a key part of it."

By playing the piano, Jamie is central to the performance in every way. "I have the opportunity to lead the band as more than just the singer; I'm also leading the instrumental side, and it gives me the chance to be more spontaneous."

What initially turned him on to the piano? "There was a piano in the house, though I switched to playing guitar because I thought it would impress the girls and my friends, but gradually I got into the piano again," he says. "A piano has a very powerful presence; it's very omnipotent on stage."

On tour, for practical reasons, Jamie will be writing songs on guitar. He hopes to start work on his next album by the end of the year, but British, American, Japanese and European tours are already filling up his 2004 diary. More interviews, more magazine covers, more travel. Heard it before? Yes, but not in the world of British jazz.

Jamie Cullum, York Barbican Centre, February 27, doors open 7pm. SOLD OUT.

Updated: 15:55 Thursday, February 19, 2004