My wife and I were coming out of a house in Camden where we had been viewing a flat to rent. Standing on the steps with us, the owner of the flat suddenly saw the retreating rear of his moped, two boys aboard and half a dozen of their friends pelting along behind.

Like the pair of prats we were, the owner and I tackled youth crime. When we caught up with the pedestrians, we received between us a black eye (owner) and cut lip (me), and no moped.

My main memory of this incident is rather horrid: the spit-filled mouth of the little rat-faced boy who punched me. Short, white, in a grey hooded tracksuit, he shouted at me with all the rage of Cain: the most astonishing indignation.