It is an offence under the Motor Vehicles (Construction and Use) Regulations, 1963, to fail to have a silencer or to maintain it in good and efficient working order. This is certainly a matter to which the police pay attention, but I would remind my hon. Friend that the police can take action only when they witness an offence or when competent witnesses are prepared to come forward. The onus to some extent must rest on the public. With regard to the last part of my hon. Friend's Question, I think that is rather a matter for my right hon. Friend the Minister of Transport.