Beside Ascot race course last week was an electronic police sign which showed your speed. We were in a traffic jam at the time moving at walking pace. As we approached the sign it flashed that we were doing 31 mph. Obviously on-board equipment on the car had jammed the radar signal from the sign and made it flash a silly number. I wonder how many motorists have been unfairly prosecuted for speeding. It is the easy option to pay the fine and accepted the points on the license rather than question authority.