The point is, that they can't be stopped at all. There is a way to suspect someone may at some point, which is what the UK security apparatus is aiming for but

The point is, that they can't be stopped at all. There is a way to suspect someone may at some point, which is what the UK security apparatus is aiming for but this kind of profiling will end up being a psychological analysis of whole groups of the population. The results won't be great for any of us.