Ah, the English policeman. The copper. The bobby. Old Bill. The filth, in the well-worn terminology of the London underworld. Until around the mid-1960s the British cop had one very flat foot in the comedy division. They carried no lethal weapons, wore silly helmets, and, at least for those who patrolled the streets of Cambridge when I lived there in the seventies and eighties, made their rounds on bicycles and smiled at you as they drifted past, gunless and placid in the pale East Anglian afternoon, as in a scene from an Ealing comedy.