I think our identity is pretty strong. We are nation of people from all over the world. A product of having a global empire. We are a nation who invented Democracy! Abolished Slavery! Fought to world wars to defeat Millitarism and Facism! Have over 2000 years of history and a thousand years of continuous monarchy, Invented many of the things that we now take for granted. Kicked off Industrialisation to name but a few things.
I think us Brits, whatever religion colour creed we are, are pretty clear about our identity. What we are also clear about is that the identity of a nation changes develops and is fluid. If it isn't the inevitable result is stagnation and death. Change is not something to fear it is something to grab by the horns and run with.
Tarmac you have a point. But we've dealt with that for many a year. We used to have Irish Catholic Republicans, leaving those explosives in Pubs etc and Blowing us up too. Thay were British Citizens as well you know. Its not that new. We're old hands at terrorism unlike your great nation for whom 911 was a wake up call. We were wide awake long before that!