Chris Barber is on his 50th anniverary tour, still enjoying his Dixieland and traditional jazz in a big way at the age of 72. On Thursday, he leads the Big Chris Barber Band at York Theatre Royal, that name indicating the increased size of his line-up.

"This is the band as I like to have it now, 11 musicians rather than eight," he says. "It's been like that since November 2001, and it's permanent. Risky you might say, but we felt we had to do it. We had the opportunity to do something like this, and it's been marvellous. I just find it a fantastic opportunity."

By risky, he means the financial cost involved, but his tour promoter assured the veteran trombone player that the figures would add up, and the Barber band could not be more delighted, especially Chris himself. "They used to say that half the night they'd be hanging around not playing; why couldn't they all play all the time, so we tried it and each time we played it got better and better, to the point where we had to decide whether to do it this way all the time."

The decision was Yes. "I'm having more fun now than I've had for 30 years!," says Chris. "We're calling it the Big Chris Barber Band because it may not be big enought to be a 'Big Band' - you need 16 - but it's definitely bigger Chris Barber music."

That bigger sound, with Bob Hunt on trombone, Mike Henry on trumpet and Tony Carter on clarinet and saxophone, can be heard not only in York next week but also on Chris's latest album, The First Eleven, released by Timeless Records last year. "We recorded it at the Birmingham Repertory Theatre just over a year ago, and I think it's very representative of what we do although you do change things all the time as you play," he says.

Respect for tradition on the one hand, a desire for change and innovation on the other, is the guiding principle of Chris Barber's career in what he calls 'revived archaic jazz'. His first change came early, at 19, when he was studying as a trainee actuary and bought his first secondhand trombone, turning this one-time classical violinist from a jazz fan into a jazz player.

"It was pure chance really that I ended up playing trombone. I'd started learning the violin because my father played violin and he thought I might like to do that too but I have a curvature of the spine that makes the stance for violin playing painful for me within two or three minutes," says Chris.

Hooked on jazz from the moment he heard a record on the radio at 12 - and promptly asked his mother to buy some jazz records for him - Chris regularly attended concerts by the George Webb Dixielanders and Humphrey Lyttelton's band from 1946 onwards.

"The first time you hear jazz live is fantastic," he says. "I would sit at the front, watching closely, and if anyone had asked at that time what instrument I wanted to play, I would have said the cornet, like Louis Armstromg.

"However, one day, Harry Brown, the trombonist, tapped me on the shoulder and said 'Would you like to buy this trombone?'."

The price was £6, Chris had £6.50 on him, and unable to put up an argument against the purchase, he found himself saying Yes. "It turned out not to be a very good trombone, even though Harry had used it on a recording," he says, smiling at the memory.

Nevertheless, trombone and Chris were meant for each other, and by the time he left the Guildhall School of Music, he already had his own New Orleans Jazz Band (as well as Chris Barber's Washboard Wonders, for whom he played string bass).

Fifty years later, Chris Barber's jazz is as much a tradition as trad jazz itself.

Big Chris Barber Band, York Theatre Royal, March 13, 7.30pm. Tickets: £12 to £16, ring 01904 623568.

Updated: 11:28 Friday, March 07, 2003