Joan Wasser, frontwoman of Joan as Policewoman, has an impeccable sense of occasion. For the first show in the Front Room, the South Bank Centre's newest music venue, she wears the kind of floor-length gold lamé gown more usually seen at the Oscars, and isn't ready to start until she has given the audience a low, sweeping curtsy.

If only the venue lived up to such glamour. It is basically the centre chunk of the Queen Elizabeth Hall foyer, lit with unnecessary brightness and susceptible to the clatter of the bar. Still, she says, at least it's not the usual coffin.

There's a lot about Wasser that seems middle-of-the-road. Piano ballads like The Ride and Anyone ooze sentiment: they are polished, carefully modulated, and would have Michael Parkinson nodding appreciatively over a cup of tea. But when she chats between songs you discover what a peculiar and enticing personality she actually is.

Her breathy voice makes even a mundane comment on the weather sound like a come-on in a porn movie. Talking about the designer of her dress she cries out, "Oh my God! Fuck! Sometimes it's all joy," in a way that is genuinely weird.

When the songs capture this oddness, Wasser is sublime. In Eternal Flame, she imagines herself as the Statue of Liberty; on record it sounds restrained but here the song flutters and soars beautifully.

Love and obsession are her primary concerns, but she has an effective line in caustic political songs, too. "Where are all the leftie assassins?" she demands at the beginning of Happiness Is a Violator, a direct attack on Condoleeza Rice. More striking still is a song about the Iraq war in which, over a strident handclap-led rhythm, she demands, "Are you not furious?" over and over. If her passion were always this truthful, Wasser would be irresistible.

· At the Zodiac, Oxford (01865 420042), on December 4, then touring.