In the old days...
Back in the early days of the laser speed-gun, my now retired mate in the Met tried one of them to see how useful it was. Duly dispatched to K Divisions streets, he came back to the station and presented the Sergeant his findings. The best one was Mr O Tree. On explaining that the oak tree was travelling at 40 mph, the Sarge decided it was either the machine or my mate that was defective. Guess which one it was.
The device (for those of cynical nature - ie all of you reading this)
R