A century ago the murder of a British soldier in broad daylight in London would have been an act of war. In this post-imperial and post-everything age, an atrocity leads to a task force which produces a report which is then filed in a desk drawer by the undersecretary for something or other. Like clockwork, the murder of Lee Rigby led to a task force and to a report. The report is 7 pages long. It’s possible to read it in much less than the twenty minutes that it took London police to respond to the murder in progress. You...