Pictured: The 'workman's van' disguised by police to target motorists with a hidden speed camera

And their worst fears look like being confirmed by this scruffy blue van.

For the Renault, complete with filthy paintwork and a GB sticker in its back window, is a speed trap that just happens to look like a builder's vehicle.

Scroll down for more...

Its true identity was uncovered by motorcycle enthusiasts who found photographs revealing that its numberplate was the same as a police van which was once covered in high-visibility markings and blue lights.

Critics said it was another example of revenue being prized above safety - and proved that guidelines about speed cameras were worthless.

Derbyshire police denied the van's dramatic makeover was a disguise to snare unwary road users.

The Department of Transport and the Association of Chief Police Officers' regulations recommend speed traps should be as visible as possible.

But Brian Gregory, of the Association of British Drivers, said: 'It's quite common now for police to hide their cars, their cameras or themselves.

Scroll down for more...

"We have even heard of police hiding behind gravestones.

"They are going down exactly the same route as the police in Australia and America. In one case in America an officer actually dressed up as a tramp while operating a speed trap. How long before that happens here?"

The van has been spotted mainly in lay-bys on notoriously dangerous Peak District roads that attract bikers from around the country every weekend.

To complete its makeover it has even been fitted has a tow-bar - which was nowhere to be seen when it was a marked vehicle.

Mr Gregory added: "It's certainly not in keeping with ACPO guidelines - but then the guidelines aren't worth the paper they're written on.

"It shows this is not about safety but revenue generation. In this case everyone suffers because of a small proportion of the motorcycle fraternity."

But police insist that the undercover van will be staying on patrol - claiming it targets speeders only where warning signs are already in place.

A spokesman said: "We use this equipment only on roads that have signs warning of the presence of speed cameras. What more can we do?

"Unfortunately, despite our efforts and campaigns, there are still some who continue to flout the law and put themselves and others at risk."

Four years ago officers in Derbyshire agreed to take down a fixed speed camera found to be hidden just two yards behind a 30mph sign on a bend on the A6 near the village of Ambergate.

Police, who claimed it had never been turned on, removed it after accepting it was "inappropriate" and didn't give motorists "a fighting chance".

Earlier this year police in North Wales converted a horsebox into a 'stealth' speed camera as part of a crackdown on speeding bikers.

Latest figures show almost two million speeding tickets are being issued to drivers each year.

Since Labour came to power in 1997 the number has shot up from 700,000 to 1.9million.

It follows the Government's huge expansion of the speed camera network. There are now around 6,000 such cameras in operation in England and Wales.