Natural Acoustics: Rodrigo y Gabriela

YOU'D THINK a pair of former thrash-metal heads from Mexico City would have the kind of backstage rider that was a hedonistic Eden. Not a bit of it. When R2 wanders into the dressing room area to wait for Rodrigo y Gabriela to finish their sound-check at Birmingham's O2 Academy, the scene is an exemplar of abstemiousness. Various juices and fruits jostle for position in the fridge, at the bottom of which sits a six-pack of beer almost determined not to draw attention to itself, as though it were a gatecrasher at a temperance society gathering.