Dr John; The Forum, London

Lauded as one of the seminal New Orleans R&B artists, Malcolm Rebennack, aka Dr John, is the kind of musician who would be revered by the obsessive record buyers in Nick Hornby's novel High Fidelity - and rightly so. By 1962, he'd chalked up countless sessions for such renowned producers as Phil Spector and Sonny Bono. Later on, his creole and psychedelia- tinged 1968 classic "Gris Gris" was a favourite with The Stooges, and more recently he played piano on Spiritualized's voodoo-esque epic "Cop Shoot Cop." He has also been a junkie, a jailbird and a shooting victim in his time. Put simply, Mr Rebennack has lived a bit.

Tonight, his band kick-off with "Iko Iko" from 1972's much-loved Gumbo album, guitarist Bobby Broom laying down some delicious, chicken-scratch Telecaster chops as Dr John saunters on stage wearing a baggy black suit and a white panama hat. His dance moves - part soft-shoe shuffle, part rain-dance - are as distinctive as Michael Jackson's moon-walk, and with his wooden cane swinging in one hand, he oozes charisma.

The set is predominantly R&B and funk based, but there are Dixieland flavours, too, and at one point we even get a couple of choruses of "Down By The Riverside", and it's as stirring and uplifting as only a gospel- standard can be. The audience is surprisingly young. Many of them couldn't have been born when Dr John released his first album, and one assumes they've come to his music through mum, dad, or the recommendation of contemporary hipsters such as Primal Scream.

Many of the songs feature break-down sections in which all four band members play percussion. During the emotive classic "Walk on Gilded Splinters" (naturally, this much-covered song draws one of the biggest cheers of the evening), drummer Herman Ernest adds eerie, echoing whistle to the big, swampy groove as our enigmatic host raps on a wood block. It's primal, sexy and completely intoxicating, and the first few rows of the audience are shaking their tail-feathers without reserve.

Dr John's piano playing is incredible, of course. He's fond of big, heavily syncopated, octave riffs and beautiful cascading lines in which the fingers of his right hand ripple like toppling dominoes as he emphasises the blue note in the cluster. His solo intro to "Such a Night" has a wonderful, bourbon-soused, bar-room feel. One quickly realises that, stylistically, this is the well-spring of much of Tom Waits' ivory-tickling.

Then there's his voice. All body and no detritus, Dr John's delicious, treacly rasp is the aural summation of more than 40 years of due-paying. "How come my dog don't bark when you come round?", he booms on "Dog", hardly needing the microphone. Then, as his band growl, howl and whimper, he goes into a wonderfully slinky piano solo which, with respect, makes you realise what Jools Holland has yet to learn.

Tonight's concert was a rare treat - a four-way virtuoso performance which completely side-stepped cerebral wank to move you with earthy, charmed music that came up through the floorboards of New Orleans bar-rooms. Right at the end, an over-zealous fan jumped up on stage and tried to sit down at the piano which Dr John had just vacated. He was pole-axed and bundled off by an over-zealous security man. One hopes a voodoo-doll effigy of the said bouncer is being stuck with pins at this very moment.

James McNair