I‘m ashamed to say that I can’t remember whether or not I met PC Keith Palmer, the policeman murdered by Khalid Masood in Parliament last week. I have been in and out through those gates often enough, greeted in that polite, slightly wry manner that British coppers use. But, like most people, I would generally just grunt “morning,” often with minimal eye contact. (As you’ll have noticed, this is another British specialty.)

It is easy to take the police for granted, to see them almost as wisecracking gatekeepers. Palmer’s death reminded me that these smiling, sardonic men will, when the need arises, place themselves between me and a murder weapon. From now on, I’m going to thank them properly.