LANCASHIRE police bosses said they still had full confidence in their speed guns after a motorist had a conviction overturned.

Brian Wiltshire, 48, from Caton, near Preston, disputed the findings of a hand-held speed gun through the courts.

He said he was travelling at less than 30mph, despite being recorded at 39mph.

Lancashire police admitted the officer failed to check the device before use.

A Preston Crown Court judge overturned the conviction after hearing evidence that laser devices can give faulty readings if not aligned properly.

Judge Andrew Woolman said the ruling did not set a precedent. He said he would give a full ruling on his decision at a later date.

Mr Wiltshire was driving home nearly a year ago when he was pulled to the side of the road by officers using an LTI 20/20 laser device.

The designer clothes shop owner pleaded not guilty to the offence before magistrates, but was convicted in June.

He then took the case to appeal at Preston Crown Court.

Mr Wiltshire said: "I thought I was being pulled over in a routine check but was shocked to learn I had supposedly broken the speed limit.

"I feel vindicated. I believe it shows that such laser devices can be wildly inaccurate."

He also called for the hand-held guns to be stablised on a tripod to prevent "human error".

But a spokesman for Lancashire police said they are confident with the gun's reliability. The spokesman added: "In this instance the case was lost because an officer failed to carry out an administrative function."