Image source, PA Media

When Keir Starmer announced his resignation as prime minister earlier in June, he said he would stay on as an MP until the next UK general election, which is not due until 2029.

But in a surprise statement - hours before his successor Andy Burnham made his debut in the House of Commons - Starmer said he would leave his post as an MP, triggering a by-election in Holborn and St Pancras.

Starmer said he was resigning to work on issues such as international affairs and violence against women and girls.

He told the Camden New Journal, external it had been a "huge honour and privilege" to represent the London constituency for 11 years, ending weeks of speculation about whether he would remain an MP.

It now leaves his parliamentary seat in Holborn and St Pancras empty, and 15 candidates are waiting at the ballot box hoping to replace him.

Tara Mewawalla
Reporting from the Holborn and St Pancras by-election

More and more people are arriving at the count today after polls closed a short time ago.

We are expecting ballot boxes to start arriving in the next hour.

The counting here at Camden Council’s main office is spread over three floors - 144 counting staff are positioned on long tables on the upper two floors, with media below.

There has been an energetic buzz about the building as counters prepare for the night ahead, and they’ve just had an announcement to begin verification of postal ballot papers.

The big job tonight has begun.

I’ve seen party members milling around where the counting is taking place - red, blue and yellow rosettes indicate their affiliation to Labour, the Conservatives and Liberal Democrat parties.

Briony Kapoor, the candidate from the Rejoin EU Party, has also just arrived.

More journalists have also trickled in, and at least a couple Metropolitan Police officers.

Voters could be seen leaving polling stations across Holborn and St Pancras today after casting their ballots in today's by-election.

Image source, Reuters

Image source, Reuters

Image source, Reuters

Image source, Reuters

Susana Mendonça
Political reporter, BBC London

Holborn and St Pancras is a parliamentary constituency full of well-known London landmarks, from the British Museum and the BT Tower to Primrose Hill, Camden Market, and bits of Regents Park.

The north London seat stretches from Holborn, Russell Square and Bloomsbury, up past Camden Town to Chalk Farm and Kentish Town.

It’s a place where many visitors first arrive in London through the major tube and railway stations at Kings Cross, and at Euston, where construction work continues for the development of HS2.

The constituency has a lot of young people. 20-24 year olds make up the largest single age group, and just under half of its residents are aged under 30 years old, according to the latest census.

While the constituency has many affluent neighbourhoods, it is a place where the cost of living and, in particular the cost of housing, is acute for many of its residents.

It is a very expensive place to buy or rent a home, and according to figures in the last census, a significant proportion of its residents (43.3%) live in social rented housing. It’s also a part of London that has high levels of child poverty.

Tara Mewawalla
Reporting from the Holborn and St Pancras by-election

We’ve just heard from acting returning officer Jon Rowney who leads everyone here at the count through the plan for the night ahead.

He stresses that the secrecy of ballot boxes is paramount and no pictures should be taken that could identify what a constituent has voted.

He says ballot boxes have been assigned to each team of 12 counters so that they finish at around the same time, rather than by geographical areas like wards, and thanks them for their “essential” work.

Finally, Rowney says counting will begin at 22:00 sharp, with postal votes, as we await the arrival of the ballot boxes from voters who have come to the polls throughout the day.

Today's by-election is a test for Burnham and Polanskipublished at 22:03 BST

22:03 BST

Chris Mason
Political editor

This feels like a consequential and rather crunchy by-election for several reasons.

For a start, it is only happening because of the national politics of the last few years – and the resignation of Keir Starmer as prime minister. Not long after he left Downing Street, he decided to leave parliament too – vacating his seat here in Holborn and St Pancras in north London.

It is also the first by-election of Andy Burnham’s tenure as prime minister. It has been a safe Labour seat for a long, long time but the Green Party of England and Wales has been making waves since Zack Polanski became its leader – and the party performed well in the local elections in London in May.

So it is a test for Burnham and it is a test for Polanski, who is the Green candidate in this race.

Image source, Reuters

And that is where things get rather heated, given the huge row of the last few days.

The Green Party is currently eating itself alive over a motion passed at its party conference just a matter of days ago which led to Polanski being banned from Israel and his party face criticism not just from the Jewish Leadership Council and the Board of Deputies of British Jews but also from sister green parties in Europe.

Polanski, who himself is Jewish, didn’t vote on the motion which said Zionism is a form of racism and called for a single Palestinian state, meaning no Israel.

The motion passed. Polanski’s team said he was instead campaigning here in Holborn and St Pancras at the time.

He has been saying no to interviews with journalists in the last few days – the BBC’s requests have been declined.

When my colleague Emilia Belli found him campaigning earlier today, she politely but persistently put questions to him, but he didn’t answer them.

Meanwhile, the prime minister has weighed in, arguing that the motion amounted to “a completely wrong decision, a terrible judgment on the part of the Green Party of England and Wales - in effect, ruling out a two-state solution between Israel and Palestine, and for that reason it shouldn’t be supported in any way, shape or form.”

Image source, Reuters

Responding to that, the Green Party of England and Wales have put out this statement:

“This has been an emotive issue and is complex. It has rightly caused much discussion, and needs to be taken in the context that Israel’s behaviour has had. Israel has been responsible for a genocide, ethnic cleansing and the killing of children, and we've had a political establishment which has not only turned a blind eye but provided support.

Zack has made an unequivocal commitment that no Jewish person will be excluded or denied a voice because they are a member of a synagogue or communal organisation that endorses Zionism.”

One figure in the party said to me that “Zack has created a monster that he either can’t or won’t control.” Plenty in the party are livid.

We expect to get to put some questions to Polanski after the vote – it will be very interesting to see how he answers them, and how, even whether, he can move the party on from the biggest row of his leadership so far.

As for the by-election contest, the Greens sound decidedly less upbeat about the result than Labour do.

Polls have now closed in the Holborn and St Pancras by-election.

Votes will be counted over the next few hours, and we'll bring you the result, expected before breakfast time on Friday.

We'll be bringing you analysis and updates throughout the night so stay with us.

Why is there a by-election? Former prime minister Keir Starmer announced he would step down as MP for Holborn and St Pancras in September, triggering a by-election. The surprise statement came just hours before his successor Andy Burnham made his debut in the House of Commons.

Who are the candidates? There are 15 candidates running to become the area's next MP - here's the full list

How does the BBC report polling day? The BBC, like other broadcasters, is not allowed to report details of campaigning or election issues while polls are open.

When does voting close? 22:00 BST - if you're in the queue at your local polling station by this time you will be able to vote.

What time will we know the winner? The count will take place overnight with the result expected in the early hours of Friday.

Tara Mewawalla
Reporting from the Holborn and St Pancras by-election

The doors are open and count staff and journalists have been let into Camden Council’s main office ahead of polls closing at 22:00.

Broadcasters are setting up camera equipment and almost 150 count staff are preparing for a long night ahead as voting results are expected in the early hours of Friday morning.

Four adjudicators and 12 supervisors are also preparing to ensure everything count-wise goes smoothly.

We will bring you the latest updates right here and our correspondents are on hand to give you analysis throughout the night.

Here's who has announced they are standing in the by-election to become the next MP for Holborn and St Pancras, listed in alphabetical order:

• Labour: Sagal Abdi-Wali
• Monster Raving Loony Party: Barmy Brunch
• Conservatives: Ewan Cameron
• Independent: Tom Darwood
• Climate Party: Clare Fischer
• Workers Party: George Galloway
• Restore Britain: Tyler Johnson
• Rejoin EU Party: Briony Kapoor
• Reform UK: Pete Newman
• UK Voice safer and stronger UK: Ketankumar Pipaliya
• Green Party: Zack Polanski
• Communist League: Jonathan Silberman
• Christian Peoples Alliance: Helen Spiby-Vann
• Liberal Democrats: Patrick Stillman
• UK Independence Party: Ben Walker

Tara Mewawalla
Reporting from the Holborn and St Pancras by-election

Image source, PA Media

There's just under an hour to go until the polls close in the Holborn and St Pancras by-election.

The contest was triggered when former Prime Minister Keir Starmer announced at the start of September that he would stand down as an MP.

Fifteen candidates are running to take his place representing the north London constituency.

Voting closes at 22:00 BST, with the results likely to be declared early on Friday morning.

We'll bring you the latest updates, reaction and analysis on this page. Stay with us.