The figure quoted recently by the media (including BBC News), when reporting on the new 'talking cameras', was that there are approximately 4.2 million CCTV cameras in use in the UK. They probably got that figure from the Institute for Public Policy Research:
http://www.ippr.org.uk/ipprnorth/articles/?id= 2465
Other sources, such as this one, put the figure slightly higher, at 4.5m:
http://www.325collective.com/social-control_su rveillance_capital.html
It works out at roughly one camera per 14 people. The last time I saw any reliable-looking data, France, Germany and the Netherlands were the next three countries listed for having the greatest number of cameras in proportion to their populations. (The countries might not have been listed in that order). If I recall correctly, they all had figures roughly around one camera per 300 people. (i.e. the concentration of CCTV camera in the UK is about 20 times higher than any other European country. Many European countries have figures closer to 1 camera for every 5,000 people.
Chris