Imagine you’re a policeman assigned the task of blocking off roads for the duration of a John Reid meeting. Your cars are parked lengthwise across the road and you and two other policemen are having a jolly chat in front of them when a young guy walks around the corner, heading for the postbox opposite. Everybody stares at him, and he seems momentarily startled. He moves to cross the road, misjudges oncoming traffic (probably as a result of being a little nervous that three policemen are watching him) and two cars have to slow down. Whoo, would he feel stupid! You wonder whether he’d walk three sides of a square, in the rain, just to avoid passing you again. Purely hypothetically, would you put him onto any kind of watchlist?