Keir Starmer entered 10 Downing St on a wave of optimism after a landslide victory in the 2024 general election. His Labour party had overturned a defeat in 2019 in which the party crashed to its worst result since 1935. Labour won 412 seats, just a few shy of the 418 won by Tony Blair in 1997, a result that gave Labour a leader in office for a decade.But a little more than two years after he came to power, Starmer’s tenure is over. Over the past 24 months the popularity of the human-rights lawyer turned prime minister has plummeted,...