Re: I have to defend the police here...
I don't buy your defence. Surely if the police are to be allowed the authority to send out letters about WiFi hotspots they should have someone who is either
a) aware of the FON service
b) aware of the Google service.
I see so many instances of failure of (b) - people stuck at the unconscious incompetence state of knowledge - they know so little that they little know how little they know. Recent example: an MP's claim that the "writing is too small" in Office 365.
As it is, without a clarification about the FON service, the letter is misleading and a waste of public money - now THAT should be an offence.