ANPR - great bit of kit
(Automatic Number Plate Recognition for those who don't watch Police Camera Action or any of the ****** Wars progs
)
Fitted to a lot of cop cars, camera is constantly scanning for number plates, and beeps up if it gets one which if flagged as no insurance, or road tax, stolen etc
Also in use on the side of many dual carriageways as a mobile unit.
And mounted on poles surrounding the centre of London (as an anti terrorist thingy)
clever stuff, and actually a valid reason for why the cops don't like you using non standard fonts / spacing on number plates.