Sir Keir Starmer is to stand down as the MP for Holborn and St Pancras, triggering a by-election in the London constituency.
The Prime Minister has represented the seat since 2015. His resignation will lead to a contest to choose a new member of Parliament for the constituency.
Sir Keir became Labour leader in 2020 and led the party to victory at the 2024 general election, becoming Prime Minister.
