Most artists begin an arena show with a bang: emerging from the floor, the gods, on a hoist, everything short of being sprung headfirst from a cannon. Touring for the first time in seven years, Peter Gabriel shrugged off such rote conventions. At 8 p.m. on the dot, he shuffled on alone in a flat cap, for all the world a man with nothing more on his mind than inspecting his spuds down at the allotment.