BREAKING THE SILENCE, a dog howled, and a flock of pigeons rose on clapping wings. A tortoiseshell cat bounded across the road, its spine fully extended. Moments later there was a dull, rumbling sound; the ground trembled; windows rattled. Then it was quiet again, but only briefly, for there was a clamour of voices as people came out of buildings on both sides of the street, and in the distance, the front of a house began to crumple.