The O2 Arena is dark. A rumble transforms into what sounds like an air raid siren. Bass drones stab through, in time with bars of light above and below the stage. Shimmers appear further back, casting shadows. Electro beats kick in. Suddenly, just for a moment, the lights and sound cut out; a deep breath before the synths of Elegy begin. Spotlights hit Sam Carter as he starts to sing, the rest of the stage still murky.