It's all very well for people to describe Ray Brown as a milestone in his chosen craft - the jazz bass - as he has the kind of monumental dignity, talent and historical significance, to have earned that description. But nobody expects a milestone to walk along the road. Yet in a sense, that is what he has been doing for years, and in almost every direction, since he has a rare ability to remain identifiably himself while adapting to virtually any kind of musical challenge.

This adaptability is what has him, at almost 73, playing with Geoff Keezer and Karriem Riggins, pianist and drummer in his current trio, both of whom are almost young enough to be his grandsons. In part, it is also what has sustained him in a career lasting over 50 years, some 30 of them on the road and the rest in the studios of the West Coast, where he lives.

"How do I keep doing this?" he asks rhetorically. "Well, first you have to wake up in the morning. That'll git you started. Second, you have to love what you do. And I like to travel; if I had to stay in one place it'd run me crazy. I tried to settle once and it didn't work."

Despite his eminent place in jazz history, his introduction to the instrument on which he has been such a major figure was a complete accident. "What got me into music was, when I was a small child, my folks had records and my father liked music; he liked piano players. He wanted me to be a piano player and he used to get Fats Waller on the radio all the time and bring Fats Waller records home." That was in Pittsburgh, where he was born in 1926.

They got him a piano teacher and that might have been that, except for a problem that came up. "When I was at junior high school - I was 14 or 15 years old - I signed up for orchestra, because we didn't have any orchestra in grade school. So I was very excited. But when I went to the class I found I was with, like, 26 piano players. So you'd only get to play for about 15 minutes a week, and then you had to sit down and try to stay out of trouble the rest of the time.

"So then I noticed there were two bass players, but there was an extra bass layin' on the floor. I went over and picked it up and started messing around with it a little bit. Then I asked the teacher; I said `listen, if I play bass could I play every day?' and he said `yeah, we need another bass player'."

He admitted he didn't feel at home on the instrument at first. "But just the fact that I could do something every day was great, you know."

His first paid gig was equally fortuitous. "There was a guy I used to deliver newspapers to. He had some band, a bunch of old guys working with him, but they used to get drunk and by the time the last set came round" - he pauses to relish the thought - "they could hardly play". Brown got a tryout "and he liked the way I played, so I used to play with him on weekends, making two or three bucks a night".

Not bad for that time? "Are you kidding?" he says. "My father wasn't making but 16 bucks a week. I was making six bucks on a weekend - eight bucks sometimes."

Although he's unduly modest about his rapid emergence on the jazz scene - "there are a lotta people I played with that you never heard of", he says, with another big laugh - his rise to the forefront of the bop revolution of the 1940s was rapid. In the fall of 1945, aged 19, he was with Dizzy Gillespie, Charlie Parker and the rest of the then young lions at the cutting edge of the New York jazz scene. "And, of course, the saying was that you didn't go to New York until you could really play."

Clearly, Brown could "really play" by then. His inspirations were Jimmy Blanton, who completely revolutionised jazz bass playing in the Ellington orchestra, along with Oscar Pettiford; who also played with Ellington. "Jimmy Blanton did everything better than anybody ever did, everything. Then Oscar carried it up a couple of notches, but he was basically a very prolific soloist."

Years later, in 1972, Brown recorded a series of duets with Ellington as a tribute to Blanton and to the duets Blanton and the Duke had recorded over 30 years before.

"You know," he says, slowly and thoughtfully, "this was something that I'd wanted to do all my life. Of course, when I was young I wanted to play in that orchestra, but then as you get older you realise that nothing can be repeated. You don't do something over. You bring something else to it. But whatever was there before has been done. But when (producer) Norman Granz asked us to do this album together, he said he thought we should do something of the old stuff, just to make a kind of tribute to Mr Blanton."

Yet Brown has made too much history himself to be content with merely repeating it. He was part of the famous - or infamous - 1940s trip to the West Coast when Parker and Gillespie took bop to the unappreciative Californians. He was with Gillespie's seminal bop big band, for which he wrote several pieces, before formally linking up with his most widelyknown musical colleague, Oscar Peterson, to form a duo in 1949. That became a trio with guitarist Irving Ashby, who was succeeded by two more on guitar, first Barney Kessel, then Herb Ellis.

Later in the 1950s, Ellis left and Ed Thigpen joined on drums to form one of the most famous and cohesive trio units of its day. How did it affect his role in the group? "The main thing that changed was that I wasn't responsible solely for the time. Once you get the drums you got a partner, a strong partner. I mean, Herb Ellis and I kept time - or whoever the guitarist was - but it's easier time-wise when you have drums."

Was it more liberating harmonically? "Well, I don't know if that's the way you want to be liberated. Having a guitar there gives you something to tie your notes to."

He is also famous for having one of the most beautiful bass sounds in jazz. How much of it is the instrument he uses? "I have a French bass. It's about 134 years old, but I think, you know, basically most bass players have their own sound. Your sound comes from your hands. Whatever you pick up, you try to get the same sound that you always get whatever you have in your hands - I think that has a lot to do with it."

What of his current group? "Keezer is a very remarkable young musician. He's got good facility, but he's also got a great mind. He hears some different stuff. He always keeps you interested. He just plays stuff that you wouldn't imagine. He's not your regular, normal, B-flat jazz pianist."

And Karriem Riggins? "I think you should hear him and make some opinion. He's a young man. He's bringing what the young people have to the table, and I'm giving him what he should have from before, and he's mixing the two in. And you get something different when you mix that stuff."

And that sounds like a personal credo.

The Ray Brown Trio plays at Vicar Street on Saturday, July 10th.