Ben Aaronovitch said this quote

The problem with the so-called bloody surveillance state is that it’s hard work trying to track someone’s movements using CCTV – especially if they’re on foot. Part of the problem is that the cameras all belong to different people for different reasons. Westminster Council has a network for traffic violations, the Oxford Street Trading Association has a huge network aimed at shop-lifters and pickpockets, individual shops have their own systems, as do pubs, clubs and buses. When you walk around London it is important to remember that Big Brother may be watching you, or he could be having a piss, or reading the paper or helping redirect traffic around a car accident or maybe he’s just forgotten to turn the bloody thing on.