Picture Sir Keir Starmer in his Downing Street study, nursing a mug of terribly sensible tea, when the news arrives. Wesley, his Health Secretary, his safe pair of hands, his loyal lieutenant, has gone rogue on Europe. He has only gone and called for a “deeper trading relationship” with the continent. A sneaky sidestep back into the EU customs union dangled like forbidden fruit over the airwaves.

One imagines the Prime Minister’s jaw tightening. The glasses were adjusted, and the tea set was set down. The boy who never quite made head boy at school has finally reached the top. And now? Mutiny in the Cabinet room just days before Christmas.