Mrs P and I happened to be strolling up the Mall over the weekend. There’s a big Commonwealth of Nations Heads of State conference going on, so the Mall is lined with the 54 flags of the Commonwealth and a small army of police and other security personnel. A particularly astute reader might want to stop me there and add a correction – there are only 53 members of the Commonwealth. But he or she would be forgetting that the Commonwealth itself has a flag. And he or she would no longer seem quite so astute.