In response to RWK
a) a Mosque/Church/Synagogue/Temple whose member conspire to commit crimes are indictable. Conspiracy to commit crimes is not excusable under the umbrella of rights.
b) only if the intent is to supply information to one who wants to commit crimes. If I use the information to blow up some rock to access the the gold then, no. This parallels the question of what I do with a gun after I buy it and if the manufacturer is liable for those actions.
c) back in the late 60's and early 70's we passed a law about "inciting to riot." In this country, you incite others to riot, commit mayhem whatever, you'll go down.
d) of the three branches of government, the Justice branch arrests and prosecutes criminals and the LEO have the power to gather evidence by whatever means necessary; some of which is governed by a Judge.
e) if that association is to discuss crime, it is a conspiracy.
Under American law, we have the right to deal with these people as we see fit. If UK law is simular, let them have at it.
One more thing I might add which has nothing to do with this discussion, some of the clerics who preach hate and discontent suck up the welfare the UK provides. The nerve of some to bite the hand that feeds them.