It has been revealed that the Police/Security services have installed fake mobile phone masts to intercept phone calls. There are apparently at least 20 in the London area. So far no one has officially confirmed their existence, other than to say that measures are taken to make the country more secure and to prevent terrorism or other crimes.
Personally, I am in favour of as many security measures being taken as possible, but I do wonder whether the law is in place to allow this mass surveillance. The Home Secretary has previously said that only known suspects are targeted for surveill