It was another moment of high drama which, in an era apparently dedicated to high drama, runs the risk of being forgotten: this was the unceremonious firing last August of Sonia Khan, a special adviser to Sajid Javid. Khan was summoned to a meeting with Dominic Cummings – a cross between Voldemort and Sun Tzu, if you believe the media – which ended in her being escorted by armed police out of the door. It subsequently emerged that the chancellor hadn’t been informed of the dismissal. This scene, shocking as it was, is perhaps even better in the reimagining by Marina Hyde in The Guardian: “Did the Saj watch manfully through the net curtains of No 11?” she wondered. Whether he did or not, there was a sense in which Khan wasn’t escorted out of the door, but out of the revolving door. “Every exit is an entry somewhere else” as Tom Stoppard once put it – and that’s especially true of Westminster, the brightest stage we have, and one with an almost unlimited cast of extras. So how does this ...