We are pretty lucky here in that there are only 20 million of us and we are surrounded by water - shark infested and crocodile infested waters at that. It must be much easier to pick up potential trouble makers here than in mainland USA, for example, which has 300 million people in approximately the same area. It would be interesting to know how many potential terrorist attacks have been detected and prevented since 9/11. What we have to keep in mind is that violent political movements can attract people from any race. This can make trouble very difficult to detect as was evident in the London bombings.