The single-most important thing for a politician is the story. They develop these as a way of signalling who they are and what they stand for, which is exactly why Donald Trump acted the way he did at the weekend. He needed to demonstrate, conclusively, that things are changing; even though it's only been seven days since Barack Obama sat in the Oval Office. And, if a few innocent people get caught up along the way, well, the new president's just made his point all the more forcefully . . .