asked Her Majesty's Government:

What measures are being taken to charge individuals who use stolen or false car registration plates to avoid paying congestion charges, parking fines and other traffic penalties. [HL4290]

If an individual uses false registration plates to avoid paying charges or penalties, potentially there would be an offence of attempting to pervert the course of justice. It is also an offence under the Road Vehicles (Display of Registration Marks) Regulations 2001 to fail to display the correct registration mark on a vehicle. It is likely that the police force involved would consult the Crown Prosecution Service about whether to prosecute and for which offence in any given case.