Mayor: higher charges for gas-guzzlers hurt families

Nearly a third of London boroughs charge higher permit fees for vehicles that pollute more. Richmond launched the first emissions-related tariff last year. It charges £300 for an annual permit for cars with the biggest engines, and £450 for a second such vehicle. Previously, permits cost £45 to £100.

Now Camden, Hackney, Haringey, Islington, Kensington and Chelsea, Lambeth, Richmond, Tower Hamlets and Waltham Forest have similar schemes, and Southwark and Sutton are considering introducing them.

Today, Mr Johnson's spokesman said: "The Mayor shares the goal of the boroughs to reduce carbon dioxide emissions but he is not convinced this sort of scheme is the best way of doing so. Rather than penalise the families that own larger cars, which might be hit by this type of charge, his focus is on reducing emissions by reducing congestion."

He said Transport for London was drawing up plans to rephase traffic lights and promote cycling and walking as well as encouraging people to "drive more efficiently".

Many councils have ruled out a policy of linking parking with emissions. Bexley councillor Peter Craske said the idea was "absurd" and Colin Smith, Bromley's executive councillor for environment, said he feared residents would see graded permits as an "opportunistic" way of making money.

But Richmond's cabinet member for traffic, transport and parking, David Trigg, said: "The purpose of this policy is to change people's behaviour, specifically by encouraging them to choose less-polluting vehicles when they change cars. I am very confident it will be effective long-term."

Camden says its scheme will be "broadly financially neutral". Haringey conceded that its CO2 charges would boost income but said it hoped drivers would be encouraged into smaller cars.