Prime Minister Keir Starmer’s Labour Party suffered an embarrassing election defeat on Friday in an area of Greater Manchester that it had dominated for almost a century, a loss that underscores the breakdown of Britain’s two-party politics.The loss of one of Labour’s safest seats, in the biggest electoral test in almost a year, puts further pressure on Starmer to prove that he should keep his job following weeks of political turmoil and calls for him to resign.The left-wing Green Party’s...