I heard that it's illegal for the US government to monitor the publics communications (internet, phone, etc) without warrents, and the same goes for the British government (illegal for them to monitor our communications), so the US and UK governments have an arrangement where the US government can monitor our communications, and the UK government can monitor British citizens communications, and both governments pretend to know nothing about it

I cant remember where I heard it, it was on some TV documentary, but it sounds feasible