h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Recent research (summer 2002) shows us that CCTV doesn't work as an effect deterrent to crime. Studies show that there is an initial decrease in crime (usually around the time that the new scheme is being advertised in local press) but that crime patterns in the area soon return to their pre-scheme levels.

See http://www.crimereduction.gov.uk/cctv31.htm for a Home Office study and http://www.crimereduction.gov.uk/cctv30.htm for a Nacro study.

I saw a TV program (one of those "Follow the Police around as they deal with the trouble in x City of a Friday night" type things).

Apparently the CCTV they had in the city hasn't caused much of a reduction in crime, but has led to a reduction in the seriousness of the crimes.

For example, it hasn't stopped drunks frighting each other or attacking people, but it does mean the police can turn up sooner and stop them before so many injuries are caused.

Hardly.

They act as surveilence then it takes thr police 1 hour to reach the crime scene, although it caputurs the footage and as evedence yet it didnt stop the crime from being commited any further.

Speaking as an ex-police officer and security guard for 7 years, I can confirm that CCTV is only as effective as the quality of the system. Which, as you may have guessed, is not a priority in any corporation unless it happens to be particularly wealthy and concerned about it's safety.
Your average town centre CCTV controlled by the police or local authority, is generally High Definition so is reliable as evidence.
I've worked with HD in two stores and even then I would make a close up shot of a shoplifters face just to make sure they couldn't wriggle out of the crime.
And to defeat such techological wonders? Put your hood up, scarf over face, keep your head down and bobs-your-uncle, you've just rendered it useless
That is of course, unless there happens to be a person actually watching you and he's just radioed his friends to wait for you outside or a police officer has been despatched to help you see the error of your ways