Keir Starmer
Keir Starmer had previously said he would stay on as an MP until the next UK general election, which is not due until 2029 Keir Starmer Instagram Photo

Sir Keir Starmer is to resign as an MP just six weeks after stepping down as prime minister, triggering a by-election in one of Labour's safest London seats. The Holborn and St Pancras MP confirmed he will stand down after 11 years, despite having previously pledged to remain on the backbenches until the next general election, expected in 2029.

The former Labour leader set out his plans in an interview with the Camden New Journal on Tuesday, saying he wanted to focus on international affairs and continue his work tackling violence against women and girls.

'It has been a huge honour and privilege to represent the best constituency in the country and to have taken over from Frank Dobson, who was such a great constituency MP and a member of the last Labour government,' Starmer told the paper.

He added: 'I will now focus on other things and that will be international affairs including defence, security, trade and technology in a fast-changing world.' Starmer resigned as prime minister in July after losing the support of Labour MPs in a confidence vote, and was succeeded by Andy Burnham.

He had held Holborn and St Pancras since 2015 and led Labour to a landslide victory at the 2024 general election, where his majority stood at 11,572. The announcement gave the Conservatives fresh ammunition on a familiar line of attack.

Conservatives Seize on Starmer's Resignation as 'Yet Another U-Turn'

Tory chair Kevin Hollinrake said it was 'fitting that his final act as a member of parliament is yet another U-turn having pledged to stay on', adding that Starmer had saddled the public with a 'costly by-election for taxpayers'.

Conservative leader Kemi Badenoch struck a more pointed tone, saying she wished Starmer well but could 'understand why he would not want to spend time with the Labour MPs who treated him so badly after he won them their seats'.

Labour has not yet named a candidate for the seat, and no by-election can be called until Starmer formally resigns.

Senior party figures, speaking on condition of anonymity, say they expect to hold the constituency but are not taking it for granted.

Greens Target Holborn and St Pancras as Local Results Signal Challenge

Local election results this year point to the Green Party as Labour's main challenger in the seat, with the Greens taking 29.8 per cent of the vote across the wards that make up the constituency against Labour's 39.5 per cent.

A Green Party spokesperson said leader Zack Polanski, a London Assembly member, had 'always made it clear he would like to be a London MP', sparking speculation among local party members that he could stand.

Burnham used one of his early Commons statements as prime minister to praise his predecessor, telling MPs Starmer had 'given this country a lifetime of public service, particularly for those fighting for justice', and pointing to his work on Ukraine and the Hillsborough Law, which is still going through Parliament.

'His leadership took our party from one of its worst defeats to its best victories and created a platform to change this country for the better,' Burnham said. Starmer's rapid exit sets him apart from several of his predecessors.

Rishi Sunak remains the Conservative MP for Richmond and Northallerton two years after leaving Downing Street, while Theresa May stayed on for five years and Liz Truss served as a backbencher until losing her seat in 2024.

David Cameron and Boris Johnson, by contrast, left the Commons relatively swiftly after leaving office. What Starmer's international role will involve remains unclear, and no formal appointment has been confirmed.

The by-election, expected within weeks, will be an early test of Burnham's leadership and a signal of whether Labour's London dominance is beginning to crack. Voters in Holborn and St Pancras will now face a contest to choose his successor.

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