A cluster of pulsating lights dropped vertically from above and the tannoy barked down the night like the voice of a robot god. A searchlight exploded in the street and flooded us with white fire. From where I lay, I screwed up my eyes and could just make out the police transport, a regulation crowd-control five metres off the street, lights flashing. The soft storm of its turbines swept flapping wings of paper and plastic up against the walls of nearby buildings and pinned them there like dying moths.