HE’S the UK’s biggest jazz artist with five albums under his belt. But if it wasn’t for an appearance on Parkinson, life could be very different for Jamie Cullum.

When people talk about a life-changing moment, rarely will it have come on a TV show.

For Cullum, 30, his appearance on Michael Parkinson’s chat show in 2003 changed his career.

Cullum may be a worldwide name now, but back in 2003, having already released two albums, he was struggling to receive mainstream recognition. Parkinson, who was impressed by the pint-sized singer-pianist, took a chance and invited the Wiltshireman onto his TV show. With Cullum’s jazz-pop style, he quickly wooed the audience. His performance sparked a bidding war to sign him. The signature went to Universal Records. The whirlwind period was the culmination of years of hard work.

Cullum’s passion for music started in childhood when he looked up to his big brother Ben: “My brother was a musician and I guess I just copied him. I thought he looked cool when he’d play Eddie Van Halen guitar solos in his bedroom. I thought ‘I’ll have a go at that’.”

It wasn’t long before music had consumed the school boy: “Music was what I grabbed onto as a teenager. At school some were the football kids, some the school swots, I guess I was the music guy.”

While he kept up with his favourite hobby throughout his teens, when he attended university his educational path shifted as he took a degree in English and film studies.

“To do a music degree, you have to be able to read music and have a grasp of music theory – I didn’t have any of that at all,” Cullum explains. Despite being focused on his studies, he couldn’t let go of his musical passion and he continued to play jazz in his spare time, releasing his first album in 1999.

The LP Heard it All Before quickly sold out, although Cullum does admit: “There were only 500 and by ‘album release’, what I really mean is I was selling them out of the back of my car.”

His second album, Pointless Nostalgic, was picked up by an independent label and led to that famous TV appearance. Now his life is filled with world tours playing to thousands of people and occasionally checking the charts to see how his singles and albums are doing.

“I guess life’s changed in that I’ve got a lot busier, but I was always making music anyway. It was all I wanted to do. Obviously opportunities have come where I’ve been able to get further with my music and I’ve had the chance to work with more and more interesting people. That part of it is strange!”

One thing he can’t deny is that romantically his life has had an overhaul in the past few years. He’s newly married to model-turned-author Sophie Dahl, but is keen to keep his private life just that.

“The whole media focus on it is a bit gross. It’s private and personal and it’s just who I am really. We prefer to be quiet about us because it’s just to do with us.”

So there won’t be a reality TV programme where the two are followed around with TV cameras then? “No! That’s definitely not for us. I think people would be bored by us. There’s not that much to see really.”

Although he’s keen to keep his relationship away from the spotlight, he’s more than happy to entertain his fans.

“To have an audience is a privilege and obviously going out and playing is what I love to do. I’m proud of just being able to continue to release records and tour and be able to sustain a career.”

Cullum is particularly happy with his latest album The Pursuit: “When I look back to my start in music I think about how much I’ve grown in the music industry. When I listen to the new album in context to what I’ve done before I see a real arc upwards in terms of my musical achievement. That makes me really happy.”

So does he acknowledge the impact Parkinson had on his life?

“I was very lucky to have that opportunity. There are a few things which led to my success but that was definitely an important one.”

• Jamie plays Portsmouth Guildhall on Thursday. Tickets: 023 9282 4355