W hatever happens next, Sir Keir Starmer will be remembered as a historically consequential Labour leader. In April 2020, he inherited a smoking ruin of a party that had suffered its worst election defeat since 1935, wrecked by Jeremy Corbyn’s disastrous leadership and stained by anti-Semitism. Three years on and, quite remarkably, he has brought Labour back to the brink of office. Today, Labour is consistently 20 points ahead of the Conservatives in the opinion polls and — witness the fall of Dominic Raab — the governing party shows no sign of drawing a line under its long record of...