A network of 36 speed cameras on the M25 has caught no one in a year because none has been switched on.
Technical and legal difficulties have prevented the Highways Agency from switching on the variable speed limit cameras.
It came to light when AOL tried to find out which camera had raised the most in fines.
The Highways Agency said the necessary statutory authority was not yet in place for some of the cameras while others were subject to technical setbacks.
A spokesman told the Daily Telegraph the agency was working with police “as a matter of urgency” to address the matter.