When I was first taught history at school, our teacher, Mr Healey, would turn round and chalk various numbered points on the blackboard: events leading up to the war (whichever war it happened to be); events of the war itself; and the consequences.

I know now that historical truth is more complex and elusive than Mr Healey made it sound. But most of the basics still seem right. He told us that taxation without representation helped cause the American War of Independence. And it did.