So what do you get if you put two of Edinburgh’s most maverick and free-spirited guitar-based bands side by side in a nightclub’s upstairs café after midnight, then get them to play their own sets – at the same time? In the case of this curious and unmissable one-off alliance the result is the sort of free improv sound-clash more associated with the fabulous free-form freak-outs that clattered out of the more experimental fringes of 1960s psychedelia, all topped off with a piece of 1970s English cheese by way of a grand finale, that’s what.

The Leg are clad in mouse masks tonight, their cello, guitar and drums a maelstrom of dark-hearted melodrama. The Pineapple Chunks concur, though all are upstaged by drummer Owen Williams, whose regular routine of crawling over and under his kit is lent extra edge by the crammed-in locale that threatens to spill over and fall apart physically as much as musically.

Conceptually, such a disparate pairing resembles aspects of ‘The Working Class Go To Paradise,’ in which artist Linder Sterling set three little-known Manchester indie bands at the same time while a group of women re-enacted Shaker rituals. Here, however, the spectacle is all over in just over twenty minutes, climaxing with a post-punk metal reading of ‘Moonlight Shadow,’ Sally Oldfield’s choir-girl clear piece of twinkly prog-folk-pop that provides pretty much the only melody on offer. As he barks out the lyrics, The Leg’s Dan Mutch punches the air in triumph as a long-cherished and much misunderstood classic is reclaimed at last.