The end could be in sight for the UK police forces' favourite weapon in the battle against speed: the LTI 20-20 speed gun. A motorist in Lancashire is the second person this month to have a speeding conviction overturned after proving the inaccuracies of the speed gun used by police.

The reliability of the LTI 20-20 speed trap has been called into question over the last few years, after a number of independent tests have shown that the equipment is not accurate if set up incorrectly.

Brian Wiltshire, 48, was convicted in June last year after being clocked speeding at 39Mph in a 30mph zone. He appealed his case on the grounds that the police officer in control of the speed trap had failed to set it up correctly. After experts showed the courts that it is possible for the speed cameras to deliver false-readings, Wiltshire's conviction was overturned.

An investigation by the Daily Mail newspaper two years ago showed that parked cars can be clocked at 22Mph, while brick walls can be captured travelling at 44Mph. Other independent tests have proven that if the devices are not completely stationary, they can give wildly erroneous readings.

All eyes are now focused on a similar court case where another motorist, Darren Fernie from Lincoln, is contesting the reliability of the speed traps after he was clocked speeding 9mph over the limit.

If this case falls in favour of the accused, it could spell the end of the road for the LTI 20-20 speed camera. The Government is likely to come under tremendous pressure to withdraw the device from Britain's streets.

Meanwhile, the Lothian and Borders Safety Camera Partnership is considering installing CCTV cameras to watch over fixed speed cameras, in an effort to record rising levels of vandalism. Of course, this begs the terrifying question: if we now have cameras watching cameras, who or what on earth are we going to get to watch the cameras watching the cameras?