Joan Baez, Barbican, London

Purity, nobility and warmth

If Bob Dylan had gone the self-destructive way of Johnny Cash, the role of June Carter in his life would surely have been taken by Joan Baez. Except she wouldn't have kept him hanging on for so long.

Baez, of course, never got the chance. Dylan's vapour trail enveloped her, and it seemed a while before she could breathe freely again. But she has long since been viewable in her own right, and as the years go by she just gets better and better.

If there is another audience this year that is as moved and enthralled as Baez's was at the Barbican last week, it will be very lucky. The voice retained all its old purity, but was mellowed by age; her choice and handling of the material was impeccable; her stage presence amounted to an aura of nobility.

At 65, Baez is so much more than a survivor. Looking elegant but unfussy in black trouser suit and plain red top with matching scarf, she stood throughout the 100-minute, 18-song set, sustaining herself with sips from a mug of what she revealed to be cold tea.

It was the only cold thing about her. Baez can convey a certain primness, but from the moment she greeted us with a glorious rendition of her 1971 hit, "The Night They Drove Old Dixie Down", we were treated to an evening of unadulterated warmth.

With superb backing from guitarists Graham Maby and Erik Della Penna (Maby adding support on vocals), Baez obliged us further with heart-stopping versions of "Stand By Me" and - inevitably - Dylan's "It's All Over Now, Baby Blue".

What raised proceedings far above the level of simple nostalgia was the lasting political relevance of so much of what she sang. "With God on Our Side" raised spectres of Tony Blair's recent appearance on Parkinson. Another Dylan song, the apocalyptic "Hard Rain", was delivered with a tenderness that merely emphasised its power. But in this context the highlight of the show was that great rallying cry of Steve Earle's, "Christmas in Washington".

Baez was quick to spot the new-found appetite for all things Johnny Cash, telling a story of how he had once introduced her to his first wife ("That's what he said, 'I'd like you to meet my first wife'"), before taking on Cash's "The Long Black Veil" and turning it into an instant Baez classic. This may be the nearest Baez has ever got to being June Carter. And that's close enough.