Holborn and St Pancras By-Election 2026: Polanski's problem may be timing says expert as Greens drift

14 September - Betfair politics expert predicts Polanski will struggle

Betfair politics tipster Pip Moss believes Zack Polanski will struggle to win enough votes to challenge Labour in the Holborn and St Pancras by-election.

In his first article on the by-election, which is due to take place on 8 October, Pip discusses the latest Betfair Exchange odds, how the national UK politics picture is affecting the by candidates' chances and why timing is a big problem for the Green Party leader.

The Greens are out to 4.03/1 - from 3.613/5 when Polanski's candidacy was confirmed on Friday - to win the by-election.

Read Pip's analysis here and look out for from him before polling day in Holborn and St Pancras, including his best bets from Betfair Exchange markets that will be going live.

11 September - Polanski second favourite after confirming he will run

Zack Polanksi is the 3.613/5 second favourite to win the Holborn & St Pancras by-election with Betfair Exchange customers after the Green Party today confirmed he will be their candidate.

That gives Polanksi a 28% chance of winning the seat behind favourites Labour.

The by-election has been triggered by Keir Starmer announcing he will stand down as an MP after resigning the party leadership.

Labour have never lost the seat in any election and are the 1.331/3 favourites to do so again. The party this week selected Camden Council leader Sagal Abdi-Wali as their candidate. A child refugee who came to the UK from war-torn Somalia in the 1990s, Abdi-Wali was the subject of tweets from Reform's Zia Yusuf suggesting she was not British.

The by-election, which takes place on October 8, is a straight fight between Labour and the Greens according to the Betfair odds - Reform are the third 'favourites' at odds of 270.0269/1!

3 September - Greens 32% chance as Polanski says he wants to stand

The Green Party are 3.185/40 on the Betfair Exchange (a 32.1% chance) to win the Holborn & St Pancras by-election after their leader Zack Polanski confirmed he wants to be their candidate.

Polanski hopes to stand for the Greens in the seat vacated by former-prime minister Keir Starmer. Before he can do that, Polanski will have to be selected as the candidate by the local party, but that should be a formality.

He became leader of the Greens last year, winning the contest by 84% of the vote, and has received considerable news coverage since then. He is arguably the most high profile leader the party has ever had and his aim is to make the Greens the UK's premier electoral force to Labour's left.

At this autumn's by-election, that should present an interesting challenge for Labour who are 1.384/11 favourites to win. They have held the seat since it was invented in 1983, with Starmer succeeding Frank Dobson there in 2015. At the 2024 general election, the Greens finished third to Labour, taking 10.4% of the vote. Polanski will hope to improve significantly on that result.

His candidacy would add intrigue to the by-election and provide an early test of Labour's popularity under new prime minister Andy Burnham who returned to Westminster as an MP by winning the Makerfield by-election in June.

1 September - What has happened in Holborn & St Pancras?

Around two months after announcing he was standing down as leader of the Labour party, Keir Starmer today revealed he would also give up his position as an MP. The former PM will instead focus on international affairs.

Once an MP resigns his seat a by-election is automatically triggered.

Who are favourites to win the Holborn & St Pancras by-election?

Labour are the strong favourites to win the by-election at 1.330/100 on the Betfair Exchange.

That's no surprise given they have won the seat at every election since it was created in the 1983 General Election.

Could Zack Polanksi finally become an MP?

If there is to be a surprise winner in the constituency it will be the Green Party.

The Greens are the second favourites in the betting at around 3.02/1 with every other party at bigger than 40.039/1.

And the Greens may choose to fight the by-election with current party leader Zack Polanksi, who is currently a member of the London Assembly but surely craves a seat on the national stage in parliament.

Polanksi is on the record as saying he will fight a by-election in London, where he has lived for the past two decades.

While Holborn & St Pancras is a Labour stronghold it is a plausible battleground for the Greens to target.

When will the by-election take place?

There is no set date at the time of writing. Once Starmer formally resigns a date will be set.

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