When he entered No 10, Sir Keir Starmer staked his reputation on upholding international law. That commitment is now being put to the test after Britain’s closest ally stormed into a sovereign country and seized its leader, leaving the Prime Minister firmly between a rock and a hard place. Donald Trump’s capture of Nicolás Maduro, the Venezuelan president, and his wife Cilia Flores threatens to become a toxic disaster for Sir Keir, who is attempting to get his premiership back on track after a torrid year. Having worked hard to form a warm but fragile relationship with the erratic US...