This is a fairly old but highly important piece of information about ubiquitous spying being conducted by the United Kingdom upon their residents. It is a system of cameras on the roads connected to computers to automatically recognize license numbers on number plates (what in the U.S.A. we'd call license plates). Of course every car has a visible number where one use is for police to identify vehicles for various reasons. What's new is nifty computer technology advancements have included in improved image recognition capability, in this case automated image recognition is being used to automatically read out the license plate (number plate) numbers of cars passing by. With enough cameras on enough streets the system can track every bit of movement by every vehicle, enabling the government to track movements of everyone.
A pair of reports on The Register web site detail two phases of the system rollout in the UK. Described is a "24x7 national vehicle movement database" to log every trip on the UK's road system. They were building a control center in Hendon capable of processing 50 million number plates PER DAY. In 2005 they already had cameras in strategic locations on every motorway in the UK and intended to have a camera every 400 yards. The initial purpose was traffic speed enforcement, but would be expanded to other crimes later such as the use of untaxed vehicles, stolen vehicles, and generally denying criminals the use of the roads.
Eek! Every 400 yards? Just think of the budget required to build maintain this system.