It's a housewarming barbecue sort of affair. Norman Blake of gradually mellowing Scottish janglers Teenage Fanclub relocates to Toronto for love and meets Joe Pernice of Massachusetts twanglers the Pernice Brothers, also relocated for love. Both are long-term purveyors of breathy, pastoral indie rock indebted to Big Star – brothers from another Sister Lover – and start making music together.

This London premiere of the collaboration has a new-pals-jamming-by-the-fireside mood. From their chairs on stage, Pernice orders shots from the bar while Blake chats with the front row and readies his glockenspiel. Amid much double-act banter they slide into a loose setlist of Teenage Fanclub obscurities, Pernice Brothers numbers, an austere Zombies cover and You Was Me by another of Blake's super-duo projects, Jonny. They corpse at the chorus of There Goes the Sun, purposefully sabotage Baby Lee and tell stories about imaginary Hall & Oates gigs and plans to call the new Jonny album Dr Who's Cock. "I thought this song was about some floozy," Joe says before Blake's I Don't Want Control of You, "but it's actually about his daughter"; Norman jokes that they're about to play either Satan or The Cabbage – among the Fanclub songs least suited to being played in this arrangement.

Blake and Pernice's drawing-room badinage comes between moments of languid acoustic intensity; Pernice's bleak, acerbic bite cushioned by Blake's honeyed harmonies. On songs from their forthcoming Australia 2013 EP and the unrecorded album beyond, most of which are "about jumping off a building", they blend seamlessly, with Blake bathing in the authentic Americana he's been drifting towards for 20 years. The likes of suicide-pact ballad Follow You Down weave a dark charm, and a final rendition of the Fanclub's Everything Flows hints at the kind of magic this pastime band could work if they rolled out the big guns.

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