The six million number comes from this study: http://www.securitynewsdesk.com/bsia-attempts-to-clarify-que...

Note that six million is the high end of the estimate, with the low being a (still rather high) four million.

This study included things like hospitals, prisons and sewage works. When talking about council-operated CCTV it does not make sense to use the six million figure.

The study estimates 1 in 70 of these cameras are controlled by the local government.