The popular image of Joan Baez will forever be the long-haired beauty who introduced boyfriend Bob Dylan onstage and sang We Shall Overcome to the folk-hippy generation. Now 63, she wears a tigerish-pattern skirt and has a cashmere scarf draped delicately over a shoulder. Shorter, greyer hair notwithstanding, she could be leading a student protest.

This is the Baez the people have come to see and she doesn't disappoint, singing movingly about Woody Guthrie, Mahatma Gandhi and Martin Luther King. The surprise is that for a veteran rebel, she's hilarious. One yarn tells of a man she knew with "a cowboy hat and a horse's arse... and now he's the President!"

It would be easy for Baez to bask in her reputation, but she has kept in touch, covering songs by natural heirs such as Natalie Merchant (an exquisite Motherland) and displaying an unlikely familiarity with British comedy shows such as The League of Gentlemen ("Are you local?" she teases. "They wouldn't get that in the States.") Backed by a band, the venue's sublime acoustics frame a voice that is still the epitome of troubled dignity. Humour aside, her greatest strength is the feeling she brings to the music.

An acoustic solo section blasts back into her beginnings as the young girl who recorded, "while staring at a big dog", these songs "from the Stone Age". They have dated, but their innocence remains startling. She fast-forwards, upping the ante. The Night They Drove Old Dixie Down is poignant, Dylan's It's All Over Now Baby Blue delightfully airy. Most powerful is a clutch of anti-war material, notably a defiant rendition of Steve Earle's 2002 Jerusalem. No doubt Baez will continue until her message of peace is no longer ahead of its time.

· At Corn Exchange, Cambridge (01223 357851), tonight, then touring.