"A couple of years ago, I met a girl called Aluna Francis," a synthesised voice intones. "We started a band called AlunaGeorge." It's a succinct, intriguing start to this sold-out gig that perfectly anticipates the music that songstress Francis and math-rock escapee-turned-producer George Reid make.

After meeting through Myspace in 2009, it was Reid's remixing talents that brought the two together, his sharp, icy beats and her soft, warm vocals united by a mutual respect for Radiohead and 1990's R&B. Since then, there have been accolades and high expectations and with their debut album, Body Music, due out in July, the future looks bright.

On first glance, they are ready. Reid, his schoolboy haircut teamed with checked shirt and jeans, busies himself with his keyboard, while Francis shimmers in mirrored sunglasses and sports lux – cropped white top, low, baggy trousers – her midriff writhing. She has got the sassy confidence and expressive hands of a young Neneh Cherry, though her sugarcoated vocals edge closer to Shanice amid the contorted, slinky groove of Just a Touch.

When the song ends, however, it's as if a light is turned off in the singer, who prowls the stage with her head down, her face anxious. Her girlish vocals struggle, too, squashed by Reid's squeaky keyboards in Attracting Flies and dampened by dub in Diver. The addition of a bassist and drummer make the sparser songs fuller and more soulful, but some of their indie-inspired strangeness is lost.

Francis removes her shades for a slinky cover of Frank Ocean's Thinkin Bout You before standing shoulder-to-shoulder with Reid to play keyboards, but it's with a jubilant version of Montell Jordan's This Is How We Do It that AlunaGeorge really come alive. Following it up with the perfect skewed pop of You Know You Like It and Your Drums, Your Love, the duo depart with the big time still beckoning.

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