It is covered by the The Removal, Storage and Disposal of Vehicles (Prescribed Sums and Charges) Regulations 2008.

The police have a legal responsibility to get the road clear as fast as possible and allow the resumption of traffic. That means they have local operators with a guaranteed service level agreement to meet certain standards of response time, quality of operators and tow trucks for the recovery of vehicles. That in turn means keeping more recovery vehicles (and special equipment) available during quiet times than might be required so they can cope with a major incident or unexpected peaks. In return the participating recovery firms are guaranteed a set fee stipulated by the Regulations. Storage costs are similarly stipulated.

Without them everyone could be sitting around waiting to get three quotes and secure the cheapest deal.

Costs of recovery are normally paid by the liable driver's insurance policy unless there is only third-party insurance.