The great majority of terrorists aren't found to have any form of mental illness. However, the situation is less clear with so-called 'lone actors', 'self-starters' or pairs who aren't part of any mainstream group.
Back in June 2011, the government presented their policy on counter terrorism - sold to us as the new Prevent strategy (what I call Prevent 2.0)- which supposedly signified a radical shift from Labour's approach to stopping extremism.
For many years terrorist groups pursuing their political, religious and ideological beliefs have attacked our free and democratic way of life. Yet the largest loss of British citizens during a single terrorist attack did not occur in Britain but in the United States on 11 September 2001.