Brighton and Hove City Council has been rapped for making misleading claims about the benefits of 20 mile an hour speed limits.

The council has been pulled up by the Advertising Standards Agency (ASA) over leaflets distributed to residents ahead of the expansion of 20 mile an hour limits across the city.

The ruling comes as The Argus can exclusively reveal that there has not been a single successful prosecution involving someone suspected of speeding between 20 and 30 miles an hour since the lower limits were introduced in April 2013.

Sussex Police has revealed under the Freedom of information Act that there is one driver accused of driving over 20mph but the case is still waiting to be heard and proved in court.

The advertising watchdog found that claims made on the council leaflet – distributed prior to a public consultation over plans for phase two of the scheme.

The leaflet included statements that reducing speed limits would encourage walking and cycling, bring health benefits and reduce congestion – but the ASA has found they were unsubstantiated and misleading.

A spokesman for the ASA said: “We told Brighton and Hove City Council to ensure future ads did not make specific claims about the benefits of the scheme unless they held evidence to support them.”

The council’s misleading leaflet was investigated following complaints from campaign group Unchain the Brighton Motorist.

Sussex Police originally said it would only support 20mph speed limits when they were self-enforcing. Last year the Association of Chief Police officers issued tougher guidance to forces telling them to issue tickets for flouting the speed limit in 20mph zones.

On the first day the lower limits came into force, The Argus caught 96% of drivers flouting the rules.

The ASA found that three further claims on the council’s leaflets were fair. Including residents were in favour of the limits in residential and shopping areas, 20 mph limits lead to a reduction in collisions and the severity of casualties and that the new limits would improve quality of life.

Councillor Ian Davey, Brighton and Hove City Council’s lead member for transport, said: “The ASA adjudication clearly states there is evidence that 20mph limits reduce the number of casualties and collisions on our roads. With the number of collisions and casualties going down across the city for three consecutive years, particularly on roads with 20mph limits, speed limit reductions are clearly saving lives here in Brighton and Hove.

“We believe an additional benefit of 20mph limits is encouraging more use of sustainable transport. Independent research points to this positive outcome and we are confident ongoing studies will provide long-term proof. The ASA’s opinion is that there is not sufficient evidence this has been achieved at this point. We respect this view.”

  •  Nathan Townsend was the first person convicted of breaking the 20 mph limit after speeding up Elm Grove at 71mph last November. But this would also have been breaking the previous 30mph limit on the road.