When a nickname really hits its target, there is a satisfying beauty about it: a quippy sobriquet that catches the attention and goes to the heart of some aspect of a person’s character. It is a measure of the Conservative party’s inability to get a convincing hold on Sir Keir Starmer that they have tried tag after tag – Captain Hindsight, Sir Softy, the dismal Captain Crasheroony Snoozefest – but none has yet found its mark.