The fitting and use of sirens is controlled by the Road Vehicles (Construction and Use) Regulations 1986. Under regulation 37(5)(a) the fitting of sirens is restricted to vehicles used by specific emergency and law enforcement agencies, including the police, fire and rescue service and ambulance service.
Regulation 99(5)(a) prohibits the use of sirens on a vehicle which is stationary on a road, at any time, other than at times of danger due to another moving vehicle on or near the road, or on a vehicle in motion on a restricted road between 11.30 pm and 7 am the following morning, except for a vehicle which is being used for one of the relevant purposes specified in regulation 37(5)(a) and it is necessary or desirable to do so either to indicate to other road users the urgency of the purposes for which the vehicle is being used, or to warn other road users of the presence of the vehicle on the road.
Training and guidance on when it is appropriate to use sirens for these purposes is a matter for the individual agencies. We have not issued any guidance to the fire and rescue service as this is an operational matter for individual chief officers.