I don't know that Tony Blair has had too much choice (though I am glad about that)The establishment, our NATO treaty, The EU and our alliance and relationship with America made it almost impossible for us to sit on the sidelines.
It isn't an attack on Islam (we spent our time in Jugoslavia helping the Muslims) but a rightful attack on the people who think they can kill and main without care.America deserved and needed the support of the world over this.