Recent events in Israel and Gaza have highlighted how hard it is to orientate in the absence of clear facts. At these times of crisis, how do political leaders decide what to do? Ali Ansari and Suzanne Raine are joined by the Rt Hon Charles Clarke, who was British Home Secretary at the time of the 7/7 bombings in London, and talks about having to take the decision whether or not to close down the London transport system that day.