Live John Martyn Royal Festival Hall

John Martyn has been playing the South Bank since the late Sixties, even though he's never quite seemed at home there. He played the Queen Elizabeth Hall in 1970 with his then wife Beverley, a full electric band and a support slot from Nick Drake and, already, he was taking issue with his reputation as a slightly whimsical solo folkie. Martyn has long since shrugged off the most obvious trappings of his hippie past and established himself as a man in a suit playing electric guitar, but he's still struggling with his past, his audience's expectations and the sheer gentility of the Festival Hall.

Latterly, Martyn has also been struggling with a dodgy record deal, a lack of musical direction and his own self-destructive tendencies. He probably hadn't previously played the South Bank complex this decade. Fortunately, a new deal with the independently minded Go! Discs, home of Paul Weller, Portishead and The Beautiful South, has restored his standing as one of the great British mavericks as has his latest album and - a dreamy but funky collection of languid grooves and hiphop beats that places Martyn alongside the 'trip-hop' generation whom he first anticipated with albums such as 1977's One World.

Tonight, the currently portly Martyn ambles onstage alone in a black double-breasted suit and white shirt with his long, matted hair tied up at the back and a pair of LAPD shades, looking for all the world like a Hollywood villain. "You won't be expecting this, which is why I'm playing it," is his opening parry as he launches straight into his best-known song, "May You Never". It's his only solo number of the night; he's accompanying himself on a phased acoustic and already he's playing with the words and his phrasing, making it swing and making it new again. This is what's great about a John Martyn concert; he's always the same, but he always makes the songs a little different.

The rest of the night is devoted to getting down and dirty or soft and spacey with Martyn's accomplished band and the additional reeds of tonight's star guest, Andy Sheppard. Texture is all in Martyn's songs, which could be crudely reduced to two - the slow pleading one and the dirty, funked- up one. On the gorgeous "She's A Lover", Sheppard's agile solo is played like someone tiptoeing awestruck around something or somebody just too beautiful to grab. As this is a slow pleading one, there's an effortless segue into the haunting "Solid Air". Martyn coos, groans and blows all over the mike like a dove; as always, there's something private and therefore something almost indecently exposed about his moans and imprecations. As if to counter such naked emotionalism, there's the sheer brutality of the dirty, funked-up ones such as the semi-psychotic "I Am John Wayne', Martyn now roaring like a maddened bull over a juggernaut industrial groove, the two horns in sinuous tandem.

The majority of the seated audience seemed to have been with Martyn most of their lives, and while a few would clearly have liked to hear a little more acoustic guitar and a little less slurring, most did the chicken thing with their necks during the funky ones or snuggled up to their partners during the slow ones. At the end of two hours, people were either dancing or just beginning to sneak a look at their watches, but John was away, riding the lithe groove of "Cool Tide" like a gangster.