A full hour after their show was meant to finish, the most quixotically gifted new British outfit of the year reach the final curtain.
Fyfe Dangerfield, their red-bearded and big-springy-haired keyboard-playing front man, announces the last song of the evening. The title is unclear, but it is a track they offered free on their website as a download on St Valentine's Day last year. Something like the full complement of stage 'Mots (as opposed to those members that appear, suddenly and violently, in the audience, banging biscuit-tin percussion and more early in the set) get stuck in.
The guitarist, Lord MagRaO, is thrashing his axe to within an inch of its life and screaming "Evil, Evil" into the microphone. Capping the heady romantic mood, the song climaxes with an ear-piercing foghorn siren - leaving the audience drained and speechless but exhilarated. The opening had been awe-inspiring too. Just Dangerfield at the keyboard and the deeply hypnotic, thrumming organ lines becoming more mesmeric as a single brilliant white light burnt on stage.
Mark Everett of Eels was immediately called to mind, but then a sudden explosion of angry horns, distorted guitars, keyboards and the aforementioned guerrilla group members storming the audience pointed the way to uncharted territory.
Sonically and theatrically, the band occupy their performance space with the sort of confidence and imagination not seen since early Flaming Lips. Musically, they draw on a vast smorgasbord that includes avant-garde invention, epic pop and Seventies kitsch and prog funk.
Dangerfield's angst-ridden persona presides, suggesting a head-on collision between the cerebral explorations of Talk Talk and the interior monologues of The Cure's Robert Smith.
But they are impossible to second-guess or pigeonhole. On Sea Out, the troubled aquatic tremors of Robert Wyatt's Rock Bottom are a starting point and the band even traverse the glittery transcendence of Soft Machine prog-jazz rock. But they end up in the sort of choirboy rapture those nice lads from Keane will spend several lifetimes attempting to attain.
Prodigiously gifted in a way that few British, or American, bands of their generation can equal, Guillemots persistently make the journey from the ridiculous to the sublime.
No wonder the audience, ranging from grizzled Britpop veterans to the coolest 14-year-old girls in town, were spellbound.