Bonnie 'Prince' Billy, Queen Elizabeth Hall, London <!-- none onestar twostar threestar x fivestar -->

King of the old, weird America

Will Oldham may be the greatest songwriter of his generation, but, like Bob Dylan before him, he has no wish to be the voice of it. Like Dylan, too, he is a consummate postmodern shape-shifter, constantly overturning the expectations of his fans and shunning celebrity. He has worked under a variety of aliases, the latest and most enduring being Bonnie "Prince" Billy. A former child movie star, he also has a parallel career as an actor (his new film, Old Joy, was released in the UK last week).

Born in Kentucky, Oldham is versed in the art of the Southern grotesque, playing up his physical freakishness and exposing in his songs an inner world teeming with sexual degeneracy, existential dread and death. This relish for perversity has allowed the 36-year-old to develop a singular body of work as an outsider artist since 1992's There Is No One What Will Take of You. His somewhat nihilistic sense of humour means that he's not averse to covering Mariah Carey or R Kelly songs live.

Tonight, however, there's no R Kelly, thankfully. But that's not to say that Oldham isn't in a deviant mood. He's in London to air songs from his 12th album, The Letting Go. Recorded in Reykjavik with one of Bjork's engineers, it finds Oldham's mix of antique folk, country and blues and modern alt-rock set to strings and airy backing by the Californian folk singer Dawn McCarthy. It's a beautiful, uncharacteristically optimistic study of the redemptive power of love, and much else. It's one of his very best.

But rather than appear with The Letting Go's violinists and viola, flugelhorn and cello players, Oldham is in rollicking Crazy Horse mode. He's dressed as a Miami undertaker (dark suit, lurid green shirt) and his performance style is like an arcane form of callisthenics based on Ian Anderson's flute-playing in Jethro Tull. Snarls flash out from under a bushy Irish-terrier beard; a hanky is camply applied to a vast, sweating head; his guitar is attacked lustily. It's fantastically entertaining stuff.

Of the new songs, "Love Comes to Me" is transformed from beatific romantic ballad to stately waltz, with brush drums, piano accompaniment and McCarthy's more-rootsy-than-usual vocals. "I'm a hard-hearted honey-pot shepherd and I'm longing to be born for you," Oldham croons gleefully. "Cursed Sleep", minus strings, is given a country-blues workout reminiscent of Ryan Adams in full flight. The Neil Young-style makeover of "Wai" renders its courtliness almost unrecognisable.

The echoes of early Neil Young and Dylan's Planet Waves resound through the improvisations on the new songs "Bad News", "God's Small Song" and "I Called You Back", which here sound like visceral outtakes from 1995's Viva Last Blues. Bantering with his cocky keyboardist, Oldham has fun with his band, which includes the gifted drummer Alex Neilson, and makes Dylan-style play with his songs. That they can be retooled so successfully is proof of Oldham's prodigious song-writing talent.

Older songs are also subjected to what Oldham has called "rescuing". The Nick Drake-like "Master and Everyone" is opened out into a kind of Flaming Lips-esque psych-rocker, with spacey keyboards. Oldham has in the past been at pains to disavow his traditionalist image, stressing an upbringing spent listening to Husker Du and Dinosaur Jnr, and there are traces of J Mascis's funnelling of Neil Young in the re-castings of "Werner's Last Blues to Blokbuster", "Wolf Among Wolves" and "Pushkin".

Oldham, though, still has a deep connection to the roots of US music, as is apparent in two fabulous covers. "John the Baptist" is an hilarious conflation of two songs, by John Martyn, and the Virginian gospel singer E C Ball. Fellow Kentuckians the Everly Brothers's "So Sad (To See Good Love Go Bad)" is a darkly stirring end to the evening. Yet it's the remodelling of Oldham's own work that's so invigorating tonight,keeping his songs fresh. Maybe that's another trick he's picked up from Dylan.