2024 U.K. election is set to overhaul British politics. Here’s what to know as Labour projected to win

London — British voters voted Thursday in the United Kingdom’s first general election since 2019, with an exit poll projecting the Labour Party notching 410 seats for a decisive win over the Conservative Party.

Among those seen heading to their local polling stations were incumbent Prime Minister Rishi Sunak, whom Conservative Party voters were forecast to boot from power after 14 years running the government, and his chief rival and likely replacement, Labour Party leader Keir Starmer.

Here’s what to know about the 2024 British general election.

Who is up for election in the U.K.?

British voters were not directly electing a new leader on Thursday. Under the United Kingdom’s parliamentary system, voters choose their local representatives for the lower house of Parliament, the House of Commons.

On Thursday, there are 650 parliamentary seats up for grabs, each of which will be occupied by one Member of Parliament (MP) in the House of Commons. For any single party to win an outright majority in the Commons, it would need to win at least 326 seats — over half of those available. Any party that does that gets to form the next government, with its leader becoming the prime minister.

An exit poll projected the Conservative Party garnered just 131 seats, with the Labour Party forecast to win 410 seats.

[Yes, King Charles III is Britain’s formal head of state. You can read here about what limited power that actually conveys.]

Parliament was formally dissolved on May 30 when Sunak called the election, as is procedure, but prior to that, Sunak’s long-ruling Conservative Party held an outright majority of 345 seats, giving it significant power to set the policy agenda.

The U.K. has what is called a first-past-the-post system, which means voters receive a ballot paper with a list of candidates from different parties and select only one of their choice. The candidate from each constituency with the most votes wins the seat — with no specific threshold required. So if, for instance, there are six candidates in a particular race, they will all be from different parties, and even if the candidate with the most votes only wins 25% of the total, they still win the seat.

If a voter believes their favorite candidate has a low chance of winning, they can choose to vote tactically and put their X next to another candidate’s name — effectively a second choice — if they feel that candidate has a better chance of winning. This tactic is generally seen as a way for a voter to help block a candidate deemed highly unfavorable, but who stands a reasonable chance of winning, from gaining the seat in a race.

In practice, this system means that a political party could win a healthy share of votes on a national level but not win a proportional share of the seats. Smaller political parties in the U.K. have long argued that the first-past-the-post electoral system has thus helped to cement the power of Britain’s two biggest parties — the incumbent, right-leaning Conservative Party, often called the Tories, and their main rivals, the more left-leaning Labour Party.