Guilty until proven innocent.

A national network of cameras and computers automatically logging car number plates will be in place within months, the BBC has learned.

John Catt found himself on the wrong side of the ANPR system. He regularly attends anti-war demonstrations outside a factory in Brighton, his home town.It was at one of these protests that Sussex police put a "marker" on his car. That meant he was added to a "hotlist".

This is a system meant for criminals but John Catt has not been convicted of anything and on a trip to London, the pensioner found himself pulled over by an anti-terror unit.

"I was threatened under the Terrorist Act. I had to answer every question they put to me, and if there were any questions I would refuse to answer, I would be arrested. I thought to myself, what kind of world are we living in?"

Sussex police would not talk about the case.

The police say they do not know how many cameras there are in total, and they say that for operational reasons they will not say where the fixed cameras are positioned.

Information Commissioner Richard Thomas, whose job it is to protect personal data, has concerns about the lack of regulation.He said:

"There's very little monitoring. I mean, my office has very limited powers."We have very limited resources. We are not actively monitoring that area. You're right to ask the question. No one's checking it at the moment"