asked the Secretary of State for the Home Department how many successful prosecutions there were in England and Wales during 1961 for causing or permitting vehicles to emit an unnecessary or excessive amount of noxious or offensive gases.

Provisional figures show that in England and Wales during 1961 there were 1,672 prosecutions under Regulation 79 of the Motor Vehicles (Construction and Use) Regulations, 1955, for the unlawful emission of smoke, etc. It is not known how many of these were successful.