Mose Allison, Pizza Express Jazz Club, London<img src="http://www.independent.co.uk/template/ver/gfx/threestar.gif"></img >

Mose Allison plays the piano - just about. He sings - just about. But it is because of his humorous, vaguely misanthropic songwriting that the 79-year-old Mississippi-born bluesman still packs out Soho's Pizza Express on his annual trips. Backed by two local players, Roy Babbington on double bass and Paul Clarvis, better known as a first-call percussionist but an excellent drummer too, Allison sat white-bearded and venerable behind the piano, his mannerisms even more exaggerated with age.

His vocals are said to have been an influence on Georgie Fame, and one can see the similarities in terms of the lack of vibrato. But Fame was blessed with a better set of pipes to begin with. In fact, Allison's singing reminds one of the wavering delivery of Willie Nelson. When he aims for a note, he does get there in the end, but not before touching a generous selection of otherson either side. Many of his songs follow the pattern of conversational sections that last as long as is necessary to fit in his oddball lyrics, at the conclusion of which comes a high note that hangs in the air until the next verse begins.

Allison's piano-playing is another curious beast. In the Fifties he'd been in bands led by Al Cohn, Chet Baker, Gerry Mulligan and Stan Getz, but his jazz chops have always been a little shaky. He has an emphatic, on-the-beat style that works well with down-the-line barrelhouse blues and in the semi-classical counterpoint sections that he drops in from time to time. There's a rigidity to it, however, that stops him from ever being able to swing entirely successfully.

But really none of this matters. Allison's imperfections are what have kept him hip all these years. He's spent decades on the sidelines, but has nevertheless been covered by everyone from The Yardbirds to Diana Krall, who recorded his "Stop This World" in 2004. He is a Bohemian, ramshackle troubadour with a diploma in the down-and-out and devious.

The highlight of his set was an outstanding reworking of "You Are My Sunshine". He stripped the song of all its sugar and changed the harmony so that much of it was in minor keys. As he lurched at the keyboard, it was as though the tune had been turned into the semi-conscious ramblings of a drunk who occasionally raised his head when illuminated by sudden sparks of hope. It was a little masterpiece of delightful dereliction.