Sir Keir Starmer has announced his decision to resign as the Member of Parliament for Holborn & St Pancras, triggering a by-election that will test the Labour Party’s ability to retain a key London seat amid growing competition from the Green Party. Starmer, who stepped down as prime minister in July, had initially intended to remain an MP until the next general election but reversed this position and will now leave Parliament immediately.
Starmer’s Holborn & St Pancras constituency has been a Labour stronghold since its creation in 1983. However, the majority he secured at the last election in 2024 was reduced to 11,572 votes, down significantly from 27,763 in 2019. This decline has coincided with an upsurge in Green Party support, particularly in the London Borough of Camden, where the Greens increased their council seats to 11 in May’s local elections, becoming the official opposition to Labour through the Green and Progressive Alliance.
The Greens, led locally by Zack Polanski, have expressed interest in contesting the by-election, with Polanski not ruling out standing as the party’s candidate. There is also speculation about a potential alliance between the Greens and Andrew Feinstein, an independent candidate aligned with the left-wing Corbynite faction who finished second to Starmer in 2024. Feinstein has called for progressive forces to unite behind a candidate opposing Labour’s platform, raising the possibility of a more consolidated challenge. However, if the anti-Labour vote remains fragmented between the Greens and Feinstein, analysts suggest it will be difficult for either to overcome Labour’s advantage.
Recent polling indicates a shift back towards Labour since Andy Burnham became prime minister. A YouGov survey from late August showed Labour support at 22 percent nationally, with the Greens trailing at 13 percent. In London, Labour’s lead is more pronounced, with 31 percent versus 17 percent for the Greens, marking the party’s lowest figures in the capital since September 2025. This polling trend offers some reassurance to Labour ahead of the by-election, although the reduced majority signifies a vulnerable position compared to previous years.
Labour has moved swiftly to fill the impending vacancy, opening candidate applications immediately with a fast-tracked selection process set to conclude by September 9. Former foreign secretary David Miliband, widely speculated to be a potential successor, has confirmed he will not seek the nomination, citing his continued work overseas with a humanitarian organization.
Starmer, who has expressed feeling “bruised” by his removal as prime minister and has long disliked the Westminster environment, indicated he is eager to focus on international affairs and campaigning against violence toward women and girls after leaving Parliament. He described representing Holborn & St Pancras as “a huge honour and privilege” and highlighted the support of his local party during his political career.
Conservative leader Kemi Badenoch expressed surprise at Starmer’s decision to stand down but understood his reluctance to continue working alongside MPs who had contributed to his departure.
The by-election in Holborn & St Pancras will be an early electoral test for Burnham’s government and a measure of whether Labour can reclaim support lost to the Greens and other progressive challengers in a part of London increasingly competitive at the ballot box.