Richie Havens, Jazz Café, London

Richie Havens's life hinged on Woodstock. His three-hour opening set at the festival, climaxing with "Freedom", his anthemic improvisation on the spiritual "Motherless Child", linked him forever to the high tide of hippie hopes. A black folk singer with touches of jazz and blues, largely dependent on covers of contemporaries such as The Beatles and Dylan, it is perhaps no wonder that he soon lost the popular attention that he grasped back then.

However, the Woodstock film has kept his urgent, incanta- tory breakthrough in some people's minds. To the whooping, eager, surprisingly young crowd tonight, he is a conduit to the Sixties, an obscure but true prince of the Woodstock Nation. It's a crown that he wears with grace, as he sets about spreading the era's most naive ideals.

Havens is 62 now, bald, with a grey, biblical beard. His first act is to arch an eyebrow, and quizzical tilts of the head, wry squints and gnomic anecdotes will punctuate his set, necessary touches of humour to leaven a message of social change delivered in almost childlike, insistently uncynical terms, holy foolery of a sort rarely seen today. Though he starts with "All Along the Watchtower", greeted as if Dylan or even Hendrix is here among us, the easy Sixties nostalgia that could be his meal ticket is deepened by this sense of current spiritual mission. He treads a fine line, hovering near the portentousness and simple, even smug moralising that punks so hated in hippies. But when he follows "Blood on the Wire" - about US imperialism's shadow-history - by stating, "We, the people of the world, actually own it", slyly widening America's Declaration of Independence for our globalised times, the steel behind his sunniness is clear.

Havens's music stays subordinate to such messages for most of the show, and the atmosphere is pleasantly earnest, rather than electric. "Freedom" changes that. "I tried not to play it once," he reveals. "They followed me out, and made me sing it in the parking lot." But instead of wearing him down, this necessary ritual seems to be what Havens stores all his energy for. "Sometimes I feel like a motherless child," he begins, the old spiritual's soul-exile sinking in. But, as he did at Woodstock, he soon has us clapping, the sound reverberating as he stands up, and for the first time you see what a big, intimidating man he is. His voice, high and light before, is suddenly raw, and he hops and shakes like a holy-roller.

Sweat glistening on his face like tears, he seems breathless, his gospel theatricality drawing us in. When he returns for an encore, he is truly praying, in a voice at last unleashed, shaking with passion for "the downtrodden". Slamming his foot for the beat, reaching towards heaven and sinking to his knees as he begs us to fight injustice, rock's religious dimension has rarely been so exposed. Sixties footnote he may be to most, but Richie Havens's festival isn't over yet.