Green Party of England and Wales co-leader Zack Polanski has confirmed he will contest the by-election for the Holborn and St Pancras constituency, the parliamentary seat held for nearly a decade by former Prime Minister Keir Starmer until his departure from the House of Commons.
The Green Party announced on Wednesday that Polanski, who shares the leadership with Carla Denyer, would stand as its candidate in the central London seat, framing the campaign around environmental policy, housing affordability, and opposition to government austerity. The move places one of the party’s two national leaders at the head of an effort to translate Green messaging into a competitive challenge in a constituency Labour has treated as a safe seat since the New Labour era.
“Polanski’s candidacy is unusual in British by-election politics in that it puts a serving national party leader directly into a contest that will inevitably be read as a verdict on the governing party’s record,” a Green Party spokesperson said in a statement reported by Al Jazeera.
What happened
Polanski confirmed his candidacy on Wednesday for the upcoming by-election in Holborn and St Pancras. The seat was vacated by Starmer, who held the constituency throughout his time as Labour leader and prime minister. Polanski said his campaign would prioritise what he described as “the cost-of-living crisis, the housing emergency, and the climate breakdown,” and would position the Greens as the main left-wing challenger to Labour in the seat.
The Green Party statement explicitly framed the by-election as an opportunity for voters to register discontent with the governing party rather than as a direct bid for parliamentary victory. The Liberal Democrats are also expected to field a candidate, and political operatives in the constituency have suggested that independent and smaller-party candidacies are likely.
The by-election date has not yet been publicly confirmed by returning officers in the London Borough of Camden, where most of the constituency falls. Under the Recall of MPs Act and standard parliamentary procedure, a writ of election must be moved within a fixed timeframe after a seat is vacated.
Why it matters
For the Green Party of England and Wales, which holds several seats in the House of Commons and a larger bloc of councillors in local government, contesting a high-profile London parliamentary seat offers a level of national visibility that internal resources cannot replicate. By-elections routinely attract disproportionate media attention relative to their share of the electoral cycle, and a campaign headed by a party leader tends to amplify that effect.
For Labour, the contest carries a more pointed set of risks. Holborn and St Pancras has returned Labour majorities at every general election since the 1990s, and the party has used the seat to platform successive shadow cabinet members, leadership contenders, and prime ministers. A comfortable Labour hold would be read as evidence that Starmer’s personal standing was the principal electoral asset and that the party’s organisational machinery in the constituency is intact. A weaker performance, particularly one in which the Greens displaced Labour in second place or cut the majority sharply, would be interpreted as a signal of progressive voter disengagement in the capital.
For the Conservatives, who finished a distant second to Labour at the most recent general election in the constituency, the contest is unlikely to alter the immediate standings, but party officials will be monitoring the size of the Green challenge as one indicator of where disaffected Labour-leaning voters are moving on the political map.
Background and context
Holborn and St Pancras covers a swathe of central and north London, including parts of Camden and the southern edge of Islington. Starmer held the seat from his first election to Parliament, and was returned with substantial majorities throughout his tenure as opposition leader and then prime minister. The constituency has been continuously represented by Labour or its predecessors since the 1930s.
The Greens have built a stronger profile in London in recent years, holding council seats across the capital and winning parliamentary representation in Bristol Central at the 2024 general election. Polanski and Denyer took over as joint leaders following the party’s decision to move to a shared leadership model, a structural change intended to broaden internal representation.
Polanski’s decision to lead the by-election campaign personally also reflects the party’s wider strategic effort to consolidate its position on the left of British politics, where it competes with independent left-wing candidates, the Workers Party of Britain, and sections of the traditional Labour vote that have expressed dissatisfaction with the governing party’s direction.
The by-election is also being shaped by the wider political environment in 2026. Polling across British politics this year has indicated a degree of voter volatility in urban seats, particularly on issues including housing, public transport funding, and the cost of living, all of which Polanski named as priorities in his announcement.
Analysis: The strategic calculus behind the candidacy
For the Greens, contesting Holborn and St Pancras is less about winning and more about leverage. A campaign that cuts the Labour majority by double digits would strengthen internal arguments for prioritising urban seats with high student populations and visible housing pressure. A weaker showing would limit the party’s room to argue for expansion beyond its current core areas.
For Labour, the contest functions as a stress test of its post-Starmer positioning. The party will be judged on whether it can hold a long-held urban seat without the personal vote of a sitting prime minister, and whether voters who previously lent Labour their ballot as a default are drifting toward the Greens, the Liberal Democrats, or independent left candidates.
For Polanski personally, leading a campaign in a seat he is unlikely to win carries both upside and risk. A disciplined campaign could consolidate his profile ahead of the next general election; a poorly managed one would expose the limits of a smaller party’s organisational reach in a complex inner-London constituency.
What to watch next
Several concrete developments will shape how the by-election is read:
– The official date of the by-election, which must be set within a statutory window after the seat was vacated. Campaigning will intensify rapidly once the writ is moved.
– Whether the Liberal Democrats field a high-profile candidate of their own, which could split the anti-Labour vote or alternatively consolidate it depending on local political dynamics.
– The Conservative candidate selection, which will indicate whether the party is treating the seat as a serious target or as a holding exercise.
– The emergence of any independent left-wing candidates, whose presence would test whether the Greens can consolidate progressive voters behind a single challenger.
– Local council data on voter registration, which will indicate whether younger and more transient voters, the groups most likely to respond to Green messaging on housing and climate, have signed up in time for the new register.
– Any polling of the constituency, which by-elections of this profile typically attract from at least one national pollster within the first weeks of the campaign.
Conclusion
The decision by Zack Polanski to stand in the Holborn and St Pancras by-election converts a routine parliamentary vacancy into a national political event. For the Greens, the contest offers visibility at limited financial cost. For Labour, it offers a measure of whether the party’s urban base will hold firm after Starmer’s exit. For voters in the constituency, it offers a choice that will be parsed, long after the result is known, as a reading of where progressive politics in central London is heading in 2026.
Sources
– https://www.aljazeera.com/news/2026/9/3/green-party-leader-zack-polanski-to-stand-in-by-election-for-starmers-seat
Source: Al Jazeera News
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Story synopsis gathered from: Al Jazeera News — source
