yeah as micky said it's not against the law.

If they are a fleet car they don't need to display anything other then the VIN number and registration.

police can use the ANPR camera to detect it'sa fleet regestered car and there for all cars are by bulk insured and taxed with the DVLA.

this applys for personalised number plates too, fleets can have minimum of 3 letters and 1 number.

as apposed to standard car where now i beleive the legal requirment is in this order 2 letters, 2 numbers, three letters.

reason being is a fleet car has it's on regestration policy like alan sugar his car is regestered as Sugar 1.

I beleive fleet/ hire cars are the only ones that can get away with it as neither driver will be the regestered owner or have his/her own insurance on that vehicle.

Taxi's, or any other commercial vehicles must show tax and have valid insurance.