With their revitalised take on the Western Swing of Bob Wills and the honky-tonk blues of Hank Williams, BR5-49 have come to save country music's dustblown, dungaree'd soul. Don't just take my word for it, though: when they made their debut appearance recently at the Grand Ole Opry, country's premier showcase, the show's venerable comedian-host Grandpa Jones was moved to proclaim, "You guys are the best band I've ever seen - and I've been to three counties!" It's an apposite testimonial: back in the Seventies, Jones was a regular on Hee Haw, a country-music TV show modelled on Laugh- In, whose blend of hayseed humour and lachrymose balladry proved a big influence on the boys in BR5-49; indeed, it's where they took their name from, this being the telephone number proferred by one of the show's comedians, Junior Samples, in a series of spoof used-car salesman pitches. "He'd speak complete gibberish for 10 seconds, a totally bizarre sales pitch, and at the end he'd hold up a little sign that said, 'The number to call is BR5-49'," explains Chuck Mead, one of the band's two singers. Yer horse is deadYer farm was repossessed todayAnd little Scotty's run awayIt looks like you'll be doin' timeSince suicide's a federal crime. Even in the conservative milieu of country music, things are moving in ever-tighter cycles.

In the mid-Eighties, Dwight Yoakam was shaking up the Nashville establishment with his hillbilly honky-tonk style and outspoken views; 10 years on, and the revolution he inspired has, through the telegenic crossover efforts of such as Garth Brooks, Billy Ray Cyrus and Travis Tritt, itself grown formulaic and corporate in tone. 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.. The mine collapsed, Ah wasn't there My dog jist died, Ah didn't care Cos when Ah'd pawned the children's toysAh had t'fight those Gatlin' boysThere's three of them and Ah'm a wimpAside from that Ah've got this limpAh got it back in VietnamWhile doin' mah bit for Uncle SamA glance across the yard revealedA crop still standing in the fieldAh watched the bourbon going downWhile Ruby took her love to townAh sent her man mah best regardsAnd thanked him for the deck of cardsAnd as Ah cried into mah beerThe band played Crystal ChandelierThen while Ah poised upon a bridgeThe sheriff waved from Chocktaw Ridge"Hold on there, son," is what he said"Ah got bad news. 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.

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.

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. 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. "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". 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. 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. 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. It's not so much a question of seeing what's in the box, as figuring out which of the contents to discard and which to keep.. John Martyn has been playing the South Bank since the late Sixties, even though he's never quite seemed at home there. But there are clearly problems of organisation when the middle-section sound- collage breakdown is more effective than the rest of the song, as on "Four Saints".