Keir Starmer announced today that he will stand down as an MP, following his removal from No10 by Andy Burnham.
The former prime minister had previously maintained that he intended to continue representing Holborn and St Pancras.
But in what may prove to be one last dramatic U-turn, Sir Keir has decided to resign his seat, setting up a potentially difficult by-election test for Labour.
Green Party leader Zack Polanski, who also serves as a London Assembly member, is weighing up whether to enter the race.
The timing of the announcement — coming just hours before Mr Burnham is due to make his debut in the Commons — could also create an opening for a senior Labour figure to return to Parliament in what is regarded as a relatively secure seat.
David Miliband has long the subject of rumours, despite repeated denials.
It immediately prompted speculation that Sir Keir could pitch for the Nato general secretary job.
Allies paid tribute to the former premier’s political career. But Mr Burnham sniped at his predecessor by telling Cabinet this morning that the public had noticed a ‘change of pace’ since he took over.
Keir Starmer is quitting as an MP after being ousted from No10 by Andy Burnham, it was revealed today
Sir Keir had a majority of over 11,000 in Holborn & St Pancras at the general election, but the Greens have been performing strongly in the polls since then
Sir Keir told his local paper, the Camden New Journal, that he was ready to ‘pass the baton to a successor’ and wanted to focus on ‘international affairs’.
‘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,’ he said.
‘I will now focus on other things and that will be international affairs including defence, security, trade and technology in a fast-changing world.
‘I will also continue, as I have done for a long time now with others, work on combating violence against women and girls; that is an issue that matters to me hugely.
‘It’s work I started before I became an MP and it’s work I’m keen to continue after I’m an MP. So international affairs on the one hand, and continuing my work on violence against women and girls on the other.’
In June Sir Keir’s spokesman was adamant that he was ‘going to remain’ as an MP at least for the rest of the Parliament.
Sir Keir himself was pressed on the question in an interview and confirmed he would stay on in the Commons.
The former PM became notorious for his U-turns during his two years in office. He could yet perform another, as despite a previous pledge not to have a resignation honours list allies have refused to rule one out.
Sir Keir has represented the north London constituency for 11 years, having been director of public prosecutions before entering politics.
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He had a majority of over 11,000 at the general election, but the Greens have been performing strongly in the polls since then.
A Green Party spokeswoman said: ‘Zack (Polanski) has always made it clear he would like to be a London MP. London has been his home for over 20 years.’
Comedy candidate Count Binface, who came second to Nigel Farage in last month’s Clacton contest, said on social media: ‘Can’t get a moment’s peace on this bloody planet.’
Sir Keir was effectively kicked out of power by Andy Burnham (pictured) in July
Conservative Party chairman Kevin Hollinrake said: ‘Whilst we have disagreed with almost all of Sir Keir Starmer’s decisions, I wish him and his family well for the future.
‘It is fitting that his final act as a Member of Parliament is yet another U-turn having pledged to stay on.
‘The decision to stand down will mean a costly by-election for taxpayers at a time when Andy Burnham and John Healey are plotting tax rises on hardworking families across the country.
‘The Conservatives look forward to giving the people of Holborn and St Pancras a chance to vote for a stronger economy and a stronger country in the weeks ahead.’
Meanwhile, Mr Burnham is finally facing a grilling from MPs this afternoon – six weeks after becoming PM.
The premier is making a statement to Parliament as it returns from the summer break.
But he could be in for a torrid time, with anger mounting over the prisoner early release scheme and the prospect of tax hikes to fund more spending.
Ministers have warned of ‘difficult’ decisions looming in the Budget, as Government borrowing costs spiked again.
Interest rates on 30-year gilts – one of the main ways the Treasury finances debt – hit 5.89 per cent this morning, the highest level since 1998.
Global markets have been spooked by inflation pressures from the Middle East crisis and fears about an AI crash.
Mr Burnham took over from Keir Starmer just as Parliament went into its break, meaning he has benefited from a ‘soft launch’ with the public’s focus largely on the sunshine instead of politics.
The new leader has gifted Labour a bounce in the polls. However that looks to be fading and the former Greater Manchester mayor has already been forced into a bewildering variety of policy shifts.
According to a Downing Street readout, Mr Burnham kicked off Cabinet by thanking his colleagues for establishing ‘a strong sense of momentum’ in his first few weeks.
‘He said the country have noticed a change of pace with the Government setting the agenda and starting the process of giving local areas the levers they need to create good growth,’ the spokesman said.
‘He said that during his summer tour, it was clear that life was hard for many people, that they wanted to have hope and hear a positive outlook for the country.’