Thirty years ago, primitive rock'n'roller The Legendary Stardust Cowboy inspired David Bowie to create his Ziggy Stardust alter ego. Now Bowie has summoned the so-called Ledge, born Norman Carl Odam, to play a rare British show at the South Bank's Meltdown festival. For the first five minutes he is hilarious: clicking his spurs, hollering over his one classic, Paralyzed, with batty gusto, hurling paper plates into the audience. Alas, the decibel level quickly spirals to distortion and the charm fades.

If an air of affable eccentricity hovers over the Ledge, Daniel Johnston is a more disturbing business entirely. Clearly fragile, he is a manic depressive whose songs are not so much tales of unrequited love as the nihilistic, obsessive poems of a troubled outsider, such as The Spook, a most aggressive plea for tolerance. A tubby figure dressed in a baggy T-shirt, sweatpants and what appear to be carpet slippers, Johnston plays wholly solo, aided only by a guitar and a lectern. His voice is that of a man much older than his 41 years. It cracks occasionally, but has the plaintive resonance of Nick Heyward or Stephen Duffy.

Mercifully, though, Johnston is not a freak show. His songs are conventionally structured and he has a real flair for melody. Mind Contorted and Casper the Friendly Ghost have dainty tunes, while the despondent Life in Vain trundles along in the merry manner of His Latest Flame.

While Johnston the songwriter needs careful nurturing, clearly Johnston the man could also do with a little assistance. Eventually his equilibrium is disturbed by a gaggle of insensitive buffoons loudly demanding his best-known song, Speeding Motorcycle ("I'm sorry, I don't have that one with me"). The set climaxes with a downbeat cover of Live and Let Die before a brief encore. The applause then is rapturous, but for Johnston it's too late. Although less than an hour has passed, he is gone for good.