They are the singing secret that the stars have kept to themselves, the vocal group with a word-of-mouth reputation for spicing up the parties of supermodels, heads of state and billionaires with their blend of razor-sharp harmonies and jaw dropping beatboxing. But now, after selling out London’s legendary Roundhouse, a series of electrifying festival appearances and a starring role in the latest T-Mobile flash-mob advert The Magnets are emerging as one of the must see acts on the current British music scene.