Traffic officers have powers to stop vehicles on most motorways and some ‘A’ class roads, in England only. If traffic officers in uniform want to stop your vehicle on safety grounds (e.g. an insecure load) they will, where possible, attract your attention by -Flashing amber lights, usually from behind -Directing you to pull over to the side by pointing and/or using the left indicator. You MUST then pull over and stop as soon as it is safe to do so. Then switch off your engine. It is an offence not to comply with their directions