As vivacious frontwomen go, Trish Keenan is in little danger of being mistaken for Gwen Stefani. A blank, baleful, virtually static presence, she stares out at a packed venue from beneath her black bangs with an air of sublime disinterest.

Yet Keenan's detachment suits the music of Broadcast, the underrated Birmingham electro-alchemists who, over their eight-year career, have shrunk from a five-piece to the duo of Keenan and multi-instrumentalist James Cargill. Tonight's set is so aloof and distanced, it appears to be taking place behind glass.

New album Tender Buttons sees the band eschew textural intricacy in favour of lo-fi primitivism: current single America's Boy is as ramshackle as a post-rock Heath Robinson. Then Black Cat sees fuzzy synth riffs buzz around nursery rhyme words like swarms of mildly irritated but benign bees.

Keenan's stonewall stage presence is heightened by her impassive, diligently deadpan vocals. Yet her alienation finds barbed resonance in the moving Goodbye Girls, a song that tackles the vexed subject of prostitutes' resentful emotional indifference towards their clients.

Broadcast attract a devoted fan base, and a pre-encore chorus of Happy Birthday for Keenan causes a temporary thaw in her cool. Like Stereolab, they are unlikely to penetrate the mainstream; their redeeming grace is that they would doubtless process this information with the most disdainful of shrugs.