Jazz; John Surman Purcell Room, London

Surman - probably the only British jazz musician whose surname alone is capable of conjuring up the gravitas associated with the great surnames of the past, like Rollins or Coltrane (though such comparisons have become irrelevant, even unseemly) - is an entirely native talent. Looking a little like a bigger version of Bill Oddie, his rich Devonian burr immediately undercuts the sense of forbidding genius suggested by his superlative saxophone and clarinet playing, rather like that old Harry Enfield sketch where the solemnity of a mock-rockumentary about a hipper- than-thou Acid Jazz group was punctured by band member Paul Whitehouse's confession that he was just up from Hampshire for the day with the wife and kiddie.

When a late-coming couple were ushered into their front-row seats after the first number, Surman greeted them with a friendly nod before, on a second thought, saying: "Think yourself lucky it's not a Keith Jarrett concert." The point being, of course, that Jarrett - Surman's label-mate at ECM Records - wouldn't dream of letting a late-comer in at all, let alone welcome them with a smile and a wink. It's not that Surman is either a yokel or a sweetie, but his generous demeanour co-exists with a talent that, in any other discipline, would be celebrated as simply the best there is.

Though he long ago blew for Britain as a soloist with Mike Westbrook, John McLaughlin and others, since his 1972 album Westering Home Surman has pursued an intermittent career of solo performance in which elements of church music, jigs and reels and long, flowing lines of almost plainsong- like plangency have created a specifically British form of improvisation, and his latest solo recording, A Biography of the Rev Absalom Dawe (on ECM), formed the text for Monday's South Bank concert.

He opened brilliantly, with a long arabesque vamp on bass clarinet, whose reedy warbling resonated through the hall as if even the air-conditioning ducts were conspiring in the breathy effects, before selecting another instrument and announcing that he'd just make the next tune up. On a strange kind of contra-bass clarinet that looked, as he said, as if it had been "recycled from the Esso refinery", he produced a deep, bowed double-bass drone that he somehow manipulated into a compelling Ellingtonian lament.

The next number came with the electronic addition of digital delay and octave-shifting effects, making Surman's soprano sax sound a bit like the primitive synth noises of Wendy (nee Walter) Carlos playing Bach, with the occasional leaps in pitch suggesting a quick inhalation of helium between the phrases. It's in his use of new tech that Surman most risks bathos: despite the skill with which he has pre-programmed an ethereal ambience or a rhythmic loop, one can't help feeling that the digital-watch sonorities of the synth work against the breathy beauty of the real-time blown and fluttered phrases. His reading from Thomas Hardy's Under the Greenwood Tree, in which a church string musician bemoans the fact that "clarinets do be bad at all times", could have served as a warning against synthesisers too, but with a player of Surman's skill and charm, it's hard to hold a grudge.

n On tour: 25 Oct Derby Guildhall (01332 255 800); 19 Nov Watermans Arts (0181-568 1176)