I do believe that "too much" freedom has its drawbacks. Most of these "clerics" (mainly arab) were given asylum in the UK as they were threatened with prison, or worse, in their own countries. In fact, some organisations (eg hizb-u-tahrir) are banned in most if not all arab countries although they are free to flourish in the UK.

This is not new. I have come across (in my university days) many followers of such organisations and they were calling for an islamic state in the uk back then. My standard response back then was that they had a moral obligation to do that in their home country (be it pakistan, algeria, libya or wherever) not in the UK. Its totally immoral to bite the hand that feeds you. I lay part of the blame on the UK government for allowing activities and organisations deemed "dangerous" in the islamic world.