Research shows that the majority of councils in Britain are either lowering or considering lowering the speed limit in residential areas.

Drivers risk fines of £100 and three penalty points for exceeding 20mph, rather than 30mph, the default limit in residential streets, in cities including Bristol, Edinburgh, Norwich, Leicester and London. According to the study by Brake, a road safety charity, 21 per cent of authorities are introducing “widespread” 20mph zones and 36 per cent are carrying out trials.

However, motoring groups argued that blanket 20mph zones were often counterproductive. Edmund King, the president of the AA, said: “If you have such a limit on a road that clearly doesn’t need it then many motorists won’t slow down and this just puts the public at risk.”

Brake obtained data from 206 local councils about their attitudes towards 20mph zones. Extrapolated across Britain, it found that 43 councils operate or plan to operate blanket 20mph limits, and 74 are proposing trials.

A spokesman for the Department for Transport said: “Research shows that 20mph zones can save lives and we have already made it easier and cheaper for councils to introduce them.”