"This time my mum didn't buy all the tickets," says Jessie Ware, surveying this jammed Brixton bar. "But her friend Phil and his bridge club did." Now that she mentions it, there are a dozen parent-aged people here, applauding vigorously from the back of the room. Though they're greatly outnumbered by 25-year-old hipsters, that balance could shift in the next few months if Ware fulfils expectations. The south London songwriter (whose father, perhaps not unhelpfully, is former BBC journalist John Ware) is being talked up as the dance underground's big 2012 crossover, and tonight's display of boundary-jumping hits-to-be suggests that success is practically hers for the taking.

On her debut album, Devotion, Ware makes chilled subtlety her calling card, drawing comparisons with Sade that aren't dispelled by the presence of a Sade-style three-piece band. Yet it's American artists who come to mind tonight: there's Chaka Khan's bittersweet intensity, and Phyllis Hyman's elegance, the latter standing her in good stead when she covers the Hyman hit What You Won't Do for Love. Ware's floating-in-space arm movements also owe something to US soul queens, and if it weren't for her effervescent chatter, you'd never know she lived in Tooting.

What initially got her noticed was a string of guest vocals for electro producers such as SBTRKT and Sampha (who's here tonight, a sweet duet partner on the Hyman song and the buoyant original Valentine), but as a solo performer her taste runs to classic material, with just enough bass juddering underneath to keep things current. Swan Song, slow and viscous with bass, is closest to her clubland beginnings, but the hymnlike, hummable Wildest Moments, which popped up in Olympics TV coverage, is her present-day, radio-friendly face. "This has been so wonderful," she says at the end, and the hipsters and Phil's bridge club unite in appreciation, cheering till the lights come on.