Some time ago a Traffic Policeman aimed his camera at me when I was exceeding the speed limit. I think his camera must have been jammed or something because the speeding ticket I was expecting never materialised. But the experience gave me such a shock that from that moment on to this day the ghost of my driving instructor reappeared in the passenger seat and I've been driving with him carefully, observantly, politely and of course meticulously keeping to all speed limits. Incidentally, I was blessed to have been taught how to drive by a good humoured Sergeant Instructor from Hendon Police College long since dead but his ghostly presence doesn't let me get away with a thing.