Five Takeaways From the U.K. General Election

A landslide victory for Britain’s center-left Labour Party is a seismic moment in the country’s politics, returning to power a party that just five years ago suffered its most crushing defeat since the 1930s.

Keir Starmer, the Labour leader, becomes prime minister with a majority of about 170 seats, almost as large as the majority Tony Blair achieved in 1997.

While Labour surged to victory, the Conservative Party crashed to the worst loss in its history, claiming only around 120 seats, lower than its previous worst result in 1906, when it won 156 seats. A new populist, anti-immigration party, Reform, burst onto the scene, winning a significant vote share though only a handful of seats. And there were striking gains for the centrist Liberal Democrats.

Here are five takeaways to help make sense of the results.

Labour is back

A party that was crushed in the 2019 general election is not just back in power but is also now the dominant force in British politics. Mr. Starmer has purged the hard left from his party and shifted Labour to the center ground, and he ran the election campaign on a simple message: “Change.”

Millions of voters returned to Labour, but the party’s share of the overall vote was modest, at about 34 percent — something of a warning sign for the new government.