Jamie Cullum: All that jazz

Jamie Cullum has just flown in to Los Angeles from Singapore. Last night he fought off the after-effects of 17 hours' travelling with buckets of beer and slops of Mexican food in a renowned LA party joint named Barney's Beanery. He was matched drink for drink by his new trumpeter, Rory Simmons, who joined Cullum's live band a few weeks ago, almost one year into the singer's current tour. Cullum didn't stop boozing till around 4.30am, winding down at a pool party at the achingly trendy Sunset Boulevard hotel The Standard. But, motored by the thoroughbred metabolism of a man not yet 27, he was still up again at 8.30am to face the music.

Another day, another continent. It's Saturday 17 June, and today the exuberant piano man begins his third American tour of 2006 with an appearance at the 28th Annual Playboy Jazz Festival, in front of a sell-out crowd of 18,000 at the legendary Hollywood Bowl. Only six months, three continents and a final, fourth American tour to go before he gets to go home to bed in his new flat in London's Kensal Green on 18 December.

"I think I've cracked it now," he reflects, as we sit in the lounge of his sleek, black tour bus parked behind the Hollywood Bowl. His face is as boyishly perky as ever, his Diddyman hair still as oddly voluminous as when he first appeared on Parkinson as the future saviour/ death of jazz a long four years ago, and he betrays not a hint of a hangover.

"I've found the balance between partying and having a great time, and getting stuff done. I've written more than I've ever written on this year's tour," he adds, lovingly patting the Edirol Midi PCR-M1 keyboard controller and silver Apple Powerbook on which he daily tinkers. There are two hard drives full of samples, "records I've chopped up just to play around with". He puts this happy accommodation of work and play down to "knowing what to expect. Before it was, 'What the hell is this?'"

It's hard to ascertain what's been the highlight of Jamie Cullum's year so far. Perhaps the American shows playing to thousands of people a night in out-of-the-way places like St Louis and Jacksonville. The knowledge that songs he's written have been recorded by as diverse a range of artists as West End songbird Laura Michelle Kelly, James Taylor's son Ben, and former boyband member (and estranged husband of Hollywood starlet Jessica Simpson) Nick Lachey. Or maybe it's the success of "Mind Trick" in Japan, which gave him his first international hit single. It propelled his second album, Catching Tales, from middling Japanese sales of 15,000 to the 100,000 mark and made him a bona-fide pop sensation in much of Asia.

This means "lots of screaming and shouting and constant presents and people shaking and crying and fainting". They were polite and respectful to Cullum's girlfriend, a Brazilian lawyer called Isabella Cannell, who had flown out from London. With the typical assiduity of a Japanese pop fan, one girl found out that he liked skulls - he wears one on a necklace all the time - and made him a brooch and bracelet. Others took the time to ascertain his sizes and the cut he likes, and presented him with bespoke T-shirts, all of which fit. Normally they're like tents on his five-foot-five frame.

Fame has brought a series of complimentary, top-of-the range Audis plus plenty of free clothes - "but they never fit. One label that fits me is Dior, 'cause they're cut really slim and small. But," he grins, "they don't give you clothes unless you're the coolest guy living in a warehouse in East London." If you're the kind of ivory-tickler who plays on Ronan Keating's new album (as Cullum has done), even a secret underground dance anthem (as Cullum has recorded with "one of the best house producers in the world") won't secure you indie credibility.

Other good times? The invitations to Elton John's hyper-A-list Oscar party - Elton's a friend, they've met a few times, he interrogated Cullum for American magazine Interview - and to his souped-up wedding to David Furnish. "The weird thing was it actually felt like an old-fashioned, traditional wedding. There were speeches, dinner and dancing ... James Blunt and his girlfriend were on my table. I sat next to Elvis Costello and [his wife] Diana Krall. Isabella sat next to Eric [McCormack] from Will & Grace, which was great 'cause she's a huge fan ... I was getting the sambucas out. I might be one of the guilty people who got David a little bit too drunk ... Michael Caine tapped me on the shoulder and said he really liked my music. I had a piss next to David Beckham ..."

And the lowlights? That could be the failure, in the UK at least, of Catching Tales. His second major label album (he'd previously released two independent ones) has sold just 250,000 copies here since it was released last September. Worldwide the album has sold 1.25m copies; f 2003's Twentysomething sold 2m. There's plenty of legs in Catching Tales yet - six further months of touring will drive more purchases, and the fact that he has so many international concert commitments points to a hefty global profile - but sales at home have fallen precipitously. Is that dispiriting for him?

"Obviously I've had to think about it," he says. "First of all, it isn't [dispiriting] 'cause it's done really well everywhere else. But I guess you have to expect it. Twentysomething became a bit more of a phenomenon than it ..."

He stops and considers the album that made him: largely a collection of covers of other people's songs done in a pleasant, confident but unchallenging, lightly jazzy way. An album that became ubiquitous as it spearheaded a mini easy-listening boom that also gave us (not that we asked for her) Katie Melua and led, to some extent, to James Blunt.

"... not more than it actually deserved," he continues. "But it became something that was more than what it actually was."

For the follow-up to his very successful breakthrough album, Jamie Cullum wanted to move on from the tinkly piano updates of standards and novelty-jazz versions of Jimi Hendrix and Jeff Buckley numbers that had made his name. He determined he would write most of the album that would become Catching Tales himself, or in tandem with people he (a) admired, (b) thought would help push forward his composition skills, or (c) hoped would broaden his range. If he was jazz-ish before, an affront to purists, he was intent now to plough his own cross-genre furrow.

He hooked up with Guy Chambers, erstwhile creative partner of Robbie Williams. He wrote with his elder brother Ben, a composer of music for, among other outlets, computer games. He sat down with minor indie troubadour Ed Harcourt, a neighbour and drinking buddy. To the music cognoscenti - whoever they are - showboating Cullum might be ickily uncool and stinkily cheesy, but cutting-edge American R&B hip-hop producers Dan the Automator and Pharrell Williams both rated his knowledge of jazz sufficiently highly to agree to collaborations.

Williams is the ultra-hip singer/knob-twiddler who gave Justin Timberlake some of his greatest songs. Unfortunately "Wifey", a song that the studio whiz originally wrote for Usher and on which Cullum did vocals, was pulled from Catching Tales at the last minute - after Cullum's record label had sent out early copies that included the song.

"That was Universal's fault, putting it on the promo version. It always had to be approved by Pharrell. I spoke to him on the phone and he said, 'I really like what you've done with it but can we just try it like this?' And we just ran out of time. And the pressure from the record company to have it on the record was so huge that I didn't want it to be on there for the wrong reasons. I also thought that a collaboration with Pharrell has to be so good and so real and so raw, it can't be second rate. No one can have any doubts about it. If something that cross-genre is gonna exist, it's gotta be great."

That is the nub of the problem with Catching Tales and Jamie Cullum '06. The album is, in ways both good and bad, all over the place. He is jazz-not-jazz, someone who is delirious to be on the same bill at the Playboy Jazz Festival as Ron Carter, Miles Davis' former bass player. But as The Hollywood Reporter would later waspishly comment in its review of Cullum's performance at the event, the "driven Brit pianist ... seem[s] like he could play a little jazz someday, but at the moment he is too breathless".

Is he an indie kid? The look and the tastes (Radiohead, Doves, Sufjan Stevens) would suggest so, and he likes being down with the Glastonbury masses. But his songs still won't frighten Parkie. He receives hip-hop "props" and knows his way round a groove, but his gigs remain nice family entertainment involving stunts with the piano, synchronised handclaps and cheery singalongs.

And that, he insists, is the way he likes it. The new songs' mix of styles is proving sufficiently adaptive to win him burgeoning audiences around the world. The ivory-tickler who was "driven" enough to fund his first album via credit card while he was studying English and film at Reading University is putting in serious time on the world's jazz festival and rock band circuit to "build a career that will last 20, 30, 40 years. It really does mean I'm setting up a global career. That means that (a) I can earn money and make more albums, and (b) I can just do music for ever and ever. That's it really."

So, he concludes firmly as showtime looms, "it's very hard for me to think of Catching Tales as technically a failure". He points out that the reviews in the newspapers and magazines he likes were largely positive. "But I can feel the record company dropping off. That's the funniest feeling." After he signed to Universal Classics and Jazz in a much ballyhooed "£1m" record deal, he remembers how "everyone used to turn up at the shows. Suddenly they drop off. And it's good to know," he insists. "You know the reality of it." Cullum smiles and gives a "what can you do" shrug.

This still-baking-hot Saturday evening, the rotating open-air stage at the Hollywood Bowl wheels Jamie Cullum and his four-piece band into the crowd's view at precisely 7.30pm. Jazzers appreciate good timing.

And, luckily for Cullum, a good time: the audience, largely black and thirty/ fortysomething and toting huge hampers of food and drinks, are at first nonplussed by this boyish little white guy in a line-up full of proper, besuited, getting-on-a-bit jazz vets. Cullum, aware that Branford Marsalis was on after him, had earlier admitted to an uncharacteristic bout of nerves.

But even before the end of the first song, "Twentysomething", Cullum has them clapping right up the back of the amphitheatre's raked seating. He pogos on the spot and sits with a discordant bump on the piano keys. He scat-sings, raps, whistles and scratches on a miniature record deck. He does a medley that encompasses Ray Charles, Jamie Foxx, Amerie and Pharrell's "Frontin'". I once saw him jump-start a conference of bankers in Barcelona. He performs similar alchemy tonight.

He repeatedly says how honoured he is to be here, and he is. He jokes that the Playboy-sponsored event brings together two of his favourite things, "jazz and naked women". There is laughter, and there is dancing. By 8.20pm it's all over. The applause ringing in his ears, bottle of Corona swinging by his side, Cullum jogs off. Ahead, an overnight drive to Oakland and tomorrow's 3,000-capacity headline gig, with support from Dan the Automator.

But he's not done with the Playboy Jazz Festival audience yet. By 8.35pm he's sat at the Tower Records stall, signing the first freshly purchased CD for the 40-plus people queuing to see him. "Hey JC!" they yell as they take his picture. Still covered in sweat, Jamie Cullum looks up and grins for the camera then bends his head back down to the job in hand.

Jamie Cullum is playing the Tower of London Festival on 13 July and Delamere Forest in Cheshire on 21 July. Visit www.jamiecullum.com/gigs for more details