That's a good point. CCTV may act as a deterrent.

It make me wonder if crime moves somewhere without CCTV (in which case we'd need a 100% coverage to win, not a good proposition).

Or, perhaps, it's not a zero-sum game. If many criminals are not "professionals", then CCTV could dramatically reduce crimes of opportunity if it does act as deterrent.

To analyze it right, I'd want to see if petty theft and other crimes of opportunity were reduced, rather than crimes like street brawling. Lumping all crime together when some are unlikely to be influenced by the cameras (because they are motivated by emotion rather than profit, for example).

If there was any discernible drop in crime rates, rest assured that they would be shouting this from the roof tops.

The only reference to any change in crime rate is "In fact, besides parking lots, few locations seem to have lower crime rates thanks to the cameras dotted around the city." There's no other mention of parking lots in the article.

Is there a significant drop in London's crime rate that isn't seen in comparable areas that are known to not have cameras?

Apparently Crime in London is at a ten year low: http://urdunews.wordpress.com/2009/01/22/london-crime-rate-d...

But the police don't seem to be giving CCTV credit for that: http://www.guardian.co.uk/uk/2008/may/06/ukcrime1

So I think it's one of those "draw your own conclusion" situations.

compared to other major world cities it is still astonishingly high though.