The first thing to know about The Polyphonic Spree is there’s a lot of them. The second thing to know is that their voices sound heavenly. But then if you bought the band’s stunning debut, you’ll already know that. To celebrate its 15th anniversary, the Spree will be performing “The Beginning Stages Of…” from start to finish. Choral symphonic rock has never sounded better. This is music on a grand scale. Over 14s only, under 16s must be accompanied by an adult.