We have yet to see the full report but the headline is that they have seen one conviction for every 1,000 CCTV cameras. They have equated this to £20,000 per conviction.
Since we have 20% of the worlds CCTV cameras in the UK (only 1% of the population though) one could argue that this is the perfect environment for a meaningful study.
The question is how many crimes does an average police officer conclude (or provide evidence leading to a conviction) each year. If it is more that one (and we suspect it is) this money is almost certainly better spent on actual Police Officers (starting wage for a Constable £22,680 PA).
"but CCTV is a great deterrent" - well... not in most cases. For the dedicated criminal there are many ways to bypass it:
1. Wear a baseball cap or 'hoddie' - we have seen countless hours of footage showing crimes being committed by people with a cap or their hood up. This negates the majority of useful evidence of any camera above eye-level (which most of them are).
2. Physically disable the cameras - spray paint, wire cutters, big stone, hammer, pointed stick etc.
3. Electronically disrupt wireless cameras - a more recent development but jamming equipment is very cheap and will easily disrupt any wireless camera (jammers are available for less than £100). Of course, you are not relying on wireless cameras for any of your mission critical functions?