The road sign before it was stolen

The sign - dubbed Smiley Sid because it smiles at motorists who keep to speed limits - was cut down by two men in a white van, according to council bosses on Teesside.

The �3,000 mobile device has been in operation at various locations in the borough of Redcar & Cleveland since September.

But it is not equipped with cameras and is used as an educational weapon in the battle against speeding drivers.

It was taken from Fabian Road in Eston on Wednesday.

The council's road safety manager Mike Hall, said he is convinced the men responsible for the theft thought they were being filmed for speeding fines.

He said: "That's the only motive I can think of.

"We've been told a white van pulled up by the device, two men got out, climbed up on the roof of the van, then used bolt cutters to cut it down.

"It's a funny scenario, but it's wanton vandalism and a crime, too.

'Good scheme'

"We've had a terrific reaction from the public about the idea.

"Everyone, apart from these two, seem to think it's a good scheme that does make motorists slow down.

"Now our problem is simple. We bought the device for a trial and I don't believe we'll be able to replace it unless the two men hear the truth behind Sid and return it to us."

The sign produces a smiley face if a driver's speed is within the speed limit and a downcast look if the driver breaks the speed limit and has the capacity to log thousands of motorists.

The data from the various locations is being analysed by the council and if there are any 'hot spots' identified, recommendations to instigate enforcement action will be passed to Cleveland Police.

The force has confirmed it is investigating the incident of 'missing Sid'.