Joan Baez, Royal Albert Hall

Dressed in Rothko reds and browns, festooned with silk scarves, bracelets and Gypsy earrings, Joan Baez at 67 is a regal presence. The pin-up girl of the Sixties folk-protest generation, with the three-octave range, is in wonderful nick. This autumn, she celebrates a half-century career with her first CD in five years, Day After Tomorrow, a new producer (Steve Earle), and a tour with a three-piece acoustic band to accompany her characterful finger-picking – unchanged from the days when she closed every concert with "We Shall Overcome."

This was an unusually intimate, reverential gig. The packed Albert Hall, with the stage area cleverly shrunk, looked like a large, warm, multicoloured living-room. The crowd featured lots of sixtysomething ladies with short haircuts that once were romantically long; and gleaming bald heads. Nostalgia was in the air like a virus. After what must have been her 49,793th rendition of Phil Ochs' "There But For Fortune", a man yelled, "We love you, Joan!" – but politely and clearly, as though recalling his heady civil-rights protest days.

Baez began with "Lily of the West", driven by blistering guitar from John Doyle. "Crimson Tide" and "God is God" were from the new album, the second written for her by Earle – a slightly soppy lyric given an edge by duelling mandolins. "With God on Our Side", written by Dylan in 1963, was given a Bush-era spin, followed by his "Farewell Angelina". Her devotion to His Bobness was nicely undercut when she sang "Love is Just a Four-Letter Word", and threw in a droll impersonation of her old lover's emphatic dee-liver-ee.

Having declared her support for Barack Obama, Baez tonight signalled her unsleeping political outrage with "Christmas in Washington". If Baez's Achilles heel has always been her earnestness, there was no danger of anyone contradicting her tonight. "Joe Hill" and "Mary Hamilton" were given extra bounce by Dirk Powell's fiddle, and "Rose of Sharon" rode on a beautiful wave of accordion. The distinctive Joan voice, so strong and Mother Courage in the contralto depths, so pure and choirgirlish in the upper strata, was splendidly showcased in the a cappella "Sing Low, Sweet Chariot".

For her third encore, Baez sang "Amazing Grace" unaccompanied – except by the whole audience, whom she led through the words until you could swear they'd all been singing with her for years. Which, of course, they have.