What type of emergency vehicle is fitted with a green flashing beacon?

Green flashing beacons on vehicles

Green flashing lights on a vehicle mean there is a doctor in the vehicle on an emergency call. Rule 219 of the Highway Code states:

Emergency and Incident Support vehicles. You should look and listen for ambulances, fire engines, police, doctors or other emergency vehicles using flashing blue, red or green lights and sirens or flashing headlights, or traffic officer and incident support vehicles using flashing amber lights. When one approaches do not panic. Consider the route of such a vehicle and take appropriate action to let it pass, while complying with all traffic signs. If necessary, pull to the side of the road and stop, but try to avoid stopping before the brow of a hill, a bend or narrow section of road. Do not endanger yourself, other road users or pedestrians and avoid mounting the kerb. Do not brake harshly on approach to a junction or roundabout, as a following vehicle may not have the same view as you.