Speed cameras on the Surrey stretch of the M25 are now active, having never been switched on since their installation in 2009.

Cameras had only been active between junctions two and three, but are now active along the entire Surrey stretch.

They could be lucrative. Highways Agency statistics show that in 2013, 139,533 vehicles a day were recorded driving past a single point on the M25 near junction 9.

A Surrey Police spokesman said: "The speed cameras on the M25 are active and the speed limit is enforceable through the cameras, and by Surrey Police's roads policing officers who carry out regular enforcement activities on the county's roadways and major routes."

Speed enforcement is managed by Surrey County Council, Surrey Police, the Highways Agency and Her Majesty's Court Service.

Cameras between junction 10 at Cobham and the M40 were due to start working by the summer of 2014. They were not on for most of the summer, and the exact date they were turned on is not yet known, but they are working now.

Claire Armstrong, co-founder of Safe Speed, said: "Motorways are our safest roads. To put speed cameras on our safest roads is nothing short of ludicrous, dangerous behaviour.

"When you start to over penalise drivers for driving faster than the legal speed limit, often by only a few miles an hour, often for a few miles of the road, does that really lead us to better road safety?"

A Highways Agency spokesman said in January of last year: "Sections of the M25 where mandatory speed limits are displayed in red rings have continued to work effectively to reduce congestion and smooth traffic flow and have operated well without fixed camera enforcement.

"We are working with Surrey Police, who are taking over responsibility between junctions 10 and 16, to resume enforcement.

"The speed limits are enforceable by the police and the cameras will be operational by summer 2014."