Buffy Sainte-Marie co-wrote Up Where We Belong, the Joe Cocker/Jennifer Warnes duet from the end of An Officer and a Gentleman, when Richard Gere appears in that blinding naval suit. She also wrote the protest song Universal Soldier, and once pulled out of a kids' TV show when she found they advertised GI Joe toys. How the legendary Cree singer reconciled her military movie smash with a lifetime of pacifism God only knows, but as she – now 71, wiry, effervescent – reminds us tonight, she had to make a living somehow, because US radio wouldn't play her records.

It's easy to see why America freaked at lyrics such as "Indian reservations are the nuclear frontline/ Uranium poisoning kills" (from The Priests of the Golden Bull). Those songs fill half of tonight's show, with words of startling clarity often set to an innocuous glam-rock backing.

Sainte-Marie reflects the strong, profoundly feminine philosophies of Antony Hegarty's Meltdown, of which this gig is part – he has compared her voice to a hex. At the same time, Sainte-Marie is a great stylist – a writer of pastiche. Piney Wood Hills was a country hit for Bobby Bare, Blue Sunday is pure rockabilly and the crooner Until It's Time for You to Go was a perfect fit for Elvis in 1972. When she first came to England she was billed as a folk singer. "I wasn't," she says tonight – "I was a songwriter, but I didn't tell anyone."

There's a fascinating clash between the pure messenger she might have been, and the career that talent allowed and politics dictated. Amid the pow-wow rock and Native American vocables, there's a cover of folk revivalist Cliff Eberhart's Goodnight, its elaborate phrases unfolding like an early Jimmy Webb song. Buffy says she wishes she'd written it. It almost sounds like she did.