The unexpected TV highlight of this year's Mercury prize ceremony was the sight of Minnie Driver, seemingly as tall as a basketball player and dressed in film-premiere pink, reducing the normally lucid Stuart Maconie to a babbling wreck during the post-match analysis. It was as if she had beamed down from Planet Hollywood (not the restaurant) specifically to make people in the music industry look short and badly dressed.

Like all film stars with musical ambitions, Driver is guaranteed attention - but attention is not the same as respect, as she appears to recognise. A few minutes into her six-song debut UK showcase, she surveys the Borderline's industry crowd and says, half-smilingly: "You've been very quiet. All quietly judging me." It might sound chippy, but she delivers it lightly and, anyway, she's right. We are all judging her.

She has done her best to defuse the novelty factor. Wearing jeans and a white blouse, she could just about pass as a regular singer-songwriter, albeit one with uncannily good hair. Only a hokey anecdote about performing on a plain ol' upright piano in a plain ol' garage, followed by a drab reading of Bruce Springsteen's Hungry Heart, finds her trying too hard to be ordinary.

When someone makes their living pretending to be other people, you hardly expect them to deliver punishing emotional exorcisms the minute they pick up a guitar, and Driver soon settles into a benign, Sunday-morning groove. However, her voice is deep and expressive, and well-built songs such as Everything I've Got in My Pocket have a warm, wraparound melancholy suggestive of a west-coast Dido. Either Driver or her co-writers has a keenly commercial songwriting instinct: each chord change falls where it should. It's not bold or idiosyncratic music, but it's good enough to be judged on its own merits rather than on its creator's celebrity, which is achievement enough.