Jamie Cullum

When Jamie Cullum plays the Cambridge Corn Exchange in October, don’t be surprised if you hear some rather over-enthusiastic whoops and squeals.

Not that the jazz supremo doesn’t deserve them. Far from it.

With his beguiling mix of earthy, jazzy pop, super-smooth vocals and puppylike on-stage energy, even the most restrained audience member would struggle not to squeal at Mr Cullum like a hyperventilating teen.

No, the explanation is a little simpler than that: “I’ve got quite a few friends who live in Cambridge, so there’ll be an unnatural amount of joke screaming when I play because all my friends will be there. It’ll be like ‘Oh my God, Jamie!’” he squeaks, “and ‘You’re a GOD!” That kind of thing. Heheheh.”

It may be first thing on a Monday morning, but Cullum is in a jovial mood – not bad for a sleep-deprived father of a baby (Margot, 6 months) and a toddler (Lyra, 2), let alone someone who’s deep in rehearsals for a hectic tour. He’s playing everywhere from Belfast to Bordeaux, promoting his sixth and latest album, Momentum - but there’s bound to be surprises, as Cullum never has a set-list.

“There’ll be moments of really deep jazz, some pop moments as well - but could go any way, really. I walk on stage and try to make it a fresh feast every night. Not even the band knows what I’m going to play.”

Crikey, isn’t that a bit exciting for them? “Yeah, but they’re used to it,” he shrugs. “If you rely on the same tricks every night, it can be like you’re going through the motions; a bit like theatre in some ways. And actually I really thrive on spontaneity on stage. It’s exhausting, but it keeps it fresh.”

Growing up in Wiltshire, the son of music-loving parents, Cullum took up the guitar and piano as a boy. His talent was unmistakable, yet he never learned read music. “I just was kind of terrible at it,” he says sheepishly. “But I’ve always found it easy to play things that I hear. Not necessarily note for note, but I can work something out just by hearing it.”

At school, he was “into everything” musically - particularly hip-hop which, with its plethora of samples, introduced Cullum to the sounds and styles of an earlier era: “It was a real link to old soul, and funk, and jazz music. But I was never the kind of kid who walked around school in a trilby, wishing I was living in the 60s,” he adds quickly. “I was going to raves and concerts with everyone else, I just had very open ears from a young age.

“When I got home from school, the first thing I would do was go to the piano or the guitar, or put music on. It was my retreat from the crippling handicap that being a teenager is. My crutch was music.”

Did he ever think he’d be famous? “No I did not!” he laughs. “I had no designs on fame. I just loved playing music, and it was a great conduit for meeting more girls and going to more parties.

“I didn’t dance around in front of the mirror with a hairbrush as a microphone, thinking I’d be on telly. In fact I probably actively didn’t want that. At that age I thought famous people were show-offs, and I just thought it was all a bit corny. I wanted to be a journalist, or a writer of some description.”

But fate had other ideas. Although Cullum studied English at the University of Reading, he played in bands – and solo in jazz clubs and restaurants – whenever he could. Famously ‘discovered’ by jazz-fanatic Michael Parkinson on his show in 2003, Cullum’s album Twentysomething went on to sell stratospherically, making him the best-selling British jazz artist of all time the same year. He was just 24.

Since then the only way has been up, not least in his personal life. In 2007 Cullum met model and author Sophie Dahl – granddaughter of the mighty Roald - at a charity event; he was to accompany her while she sang. The two became friends (she was seeing someone else at the time) but romance eventually blossomed and they married in 2010.

At the time the couple faced a lot of press interest, not least because of their height difference: Cullum is just under 5ft 5, while statuesque Dahl is nearly 6 ft (their official line is ‘It doesn’t bother us, why should it bother anyone else?’).

But being ‘papped’ is less of an issue now that they’ve settled in Great Missenden, Buckinghamshire, where granddad Dahl lived for nearly 40 years. “We live a life apart from all that really,” says Cullum. “Occasionally we’ll go to something like a charity event together, but we don’t live in London, we don’t hang out with other famous people, and we don’t go to where all the paparazzi are.”

Has becoming a dad changed his music? “I think it changes you irreparably in the best possible way,” he says. “It gives you an amazing focus that you didn’t have before. So I’m maybe a bit more open, a bit more willing to take risks, a bit less interested in what people think of it.

“But it’s more incremental than people realise. I thought it was weird that Jay Z was recording a song confessing how much he’d changed after having a kid - about six hours after the baby was born! Shouldn’t he be making his wife some tea or something?” he says, laughing again.

So it’s safe to assume we can expect some ‘more open’ and ‘riskier’ post-becoming-a-dad music from Cullum’s concert. But no doubt he’ll also be throwing in some jazz covers of the most unlikely songs. After all, whether drumming (with his hands) on top of his piano while belting out a Michael Jackson hit, or giving a morose Radiohead track a sexy new twist, it’s what his live shows are famous for.

Does he have a favourite? “I think Don’t Stop the Music, the Rihanna cover. It’s one of the most popular, and we do it every night because there’s a big improvised section in the middle which is really fun.

“Sometimes it’s four minutes long, sometimes it’s 10 minutes long. It’s just like having a conversation really — you don’t know how long it’s going to last, or exactly what’s going to be said, and then you try and get out elegantly.” And do they always get out elegantly? “Hell, no!” he laughs. “But it’s always enjoyable to watch and be a part of.

“You know, we have an amazing amount of fun on stage. There’s a huge amount of energy, and great musicianship. And it’s not like other touring shows out there – we cover a lot of different bases that you wouldn’t normally see in one night of music. We have a lot of fun and the audience always does too.”

Cue those whoops and squeals…