| Motorists caught driving at 79mph or faster on the M4 face a £60 fine and three penalty points from today.
Wiltshire police will be setting speed traps with cameras and laser guns on the busy motorway between junctions 14 (Hungerford) and 18 to catch speeders.
Although police usually stop cars clocking up over 85mph, the mobile cameras aim to prosecute anyone driving as little as 9mph over the limit.
Police claim the Wiltshire stretch of the M4 has an above average death rate, although motorways are five times safer than A roads. | 
