Ellie Goulding, Union Chapel, Islington

A year ago, Ellie Goulding was supporting Florence and The Machine at one of last year's Little Noise Sessions benefit concerts in aid of Mencap. On Saturday, she was headlining the last of this year's Little Noise Sessions at the Union Chapel.

Her debut album, Lights, presented Goulding as an electropop diva in the mould of Little Boots and La Roux, her voice tricked and treated over sleek synthesiser arrangements and pulsing drum programmes. Tonight's line-up is more notable for the string quartet and backing vocalists.

In front of them, Goulding perches on a drum stool, clad in a loose black blouse and skin-tight black leather trousers. The contrast between these and her acoustic guitar crystallises the paradox at the heart of her appeal, which has been achieved by slipping through the cracks between genres, finding space to effect an alliance between folk music and electropop.

This becomes crucial when, as soon as the opening "Under The Sheets" has finished, the entire PA system dies, leaving Goulding stranded in front of a packed house and television cameras. Gamely shouldering her guitar, she strides to the front of the stage, and belts out "Everytime You Go" as a solo number, her pure, clear voice barely reaching to the further corners of the chapel. The response is overwhelming: no sooner has the last phrase died away than the hall explodes into cheers. Not only is the girl a trouper, we exult, she can do it all on her own, without any of the technical trick-nology that disguises lesser singers' shortcomings.

"This Love (Will Be Your Downfall)" is delivered almost a cappella, and the strings lend a bittersweet Britishness to the likes of "Guns And Horses" and the wistful smalltown reminiscence "Wish I Stayed". A cover of Temper Trap's "Sweet Disposition" concludes in long, descending trails of vocal and piano, and the arrival of Ben Lovett (from Mumford & Sons) to play piano on her new single of Elton John's "Your Song" draws a few star-struck squeals from parts of the crowd.