Driver and Vehicle Standards Agency officers have powers to stop vehicles on all roads, including motorways and trunk roads, in England and Wales. They will attract your attention by flashing amber lights
It is an offence not to comply with their directions. You MUST obey any signals given (see ‘Signals by authorised persons’).
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
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 (see ‘Signals by authorised persons’).
Traffic light signals and traffic signs. You MUST obey all traffic light signals (see ‘Light signals controlling traffic’) and traffic signs giving orders, including temporary signals & signs (see ‘Traffic signs’). Make sure you know, understand and act on all other traffic and information signs and road markings (see ‘Traffic signs’, ‘Road markings’ and ‘Vehicle markings’).
Flashing headlights. Only flash your headlights to let other road users know that you are there. Do not flash your headlights to convey any other message or intimidate other road users.
Never assume that flashing headlights is a signal inviting you to proceed. Use your own judgement and proceed carefully.
The horn. Use only while your vehicle is moving and you need to warn other road users of your presence. Never sound your horn aggressively. You MUST NOT use your horn
except when another road user poses a danger.