Anyone who has tracked Boris Johnson’s career, or worked with him, or been betrayed by Bojo by accident or design, will have known why he was so chipper this week. At PMQs the Tory leader was punchy rather apologetic. Having been in so many self-inflicted scrapes since childhood, this is for Boris a familiar point in the arc of a crisis. It’s the “I’m pretty certain I’m going to get away with it” moment.