Peridot is Héctor, Aurélie, Duncan and Matthew, who hail from Spain, France, Australia and Britain respectively, and came together as a quartet in March last year. They sing a capella - that is, with no instrumental accompaniment, and usually without amplification - representing music in its oldest and primeval form. They have more years of chorus and quartet singing experience between us than they care to add up, and share a small but treasured haul of gold, silver and bronze medals from a number of chorus contests.