Disaster for Zack Polanski as Greens hit by double council by-election defeat
The council by-election defeats are a blow to Green leader Zack Polanski (Image: Getty)
The Green Party has suffered two significant council by-election defeats, losing seats in Sheffield and Leicestershire as party leader Zack Polanski prepares for one of the most closely watched parliamentary contests of his leadership.
The results provide a fresh test for the Greens after their national support increased substantially earlier in the year. They also come at a particularly sensitive moment, with Polanski due to contest the Holborn and St Pancras by-election on October 8.
However, the two council contests need to be viewed in their local context. A pair of by-election defeats does not by itself establish a nationwide trend, and the voting patterns in individual council wards can differ considerably from national opinion polling.
In Sheffield’s Walkley ward, Labour’s Hannah Cawley won with 2,315 votes, ahead of Green candidate Seb Van Bilsen Irias, who received 1,249. Reform UK finished third with 541 votes, while the Liberal Democrats and Conservatives were further behind. Turnout was 28.18 per cent, with 4,340 ballot papers issued in a ward containing 15,401 registered electors.
The result therefore represented a clear Labour gain from the Greens in a contest in which the two parties were separated by more than 1,000 votes.
The second contest, in Wreake Valley in Charnwood, produced another setback for the Greens, with the party falling to third place. The Conservatives won the seat, while Reform UK finished second.
Together, the results give Labour and the Conservatives examples of local contests in which Green candidates failed to retain seats, while Reform also demonstrated its ability to compete strongly in one of the contests.
A difficult moment before Holborn and St Pancras
The timing is particularly important for Polanski.
The Green leader is standing in Holborn and St Pancras, the north London constituency vacated by former prime minister Keir Starmer. The by-election will take place on October 8, with 15 candidates officially nominated. They include Labour’s Sagal Abdi-Wali, Polanski for the Greens, Peter Newman for Reform UK, Ewan Cameron for the Conservatives, Patrick Stillman for the Liberal Democrats and Workers Party leader George Galloway.
That means the contest is considerably broader than a simple Labour-versus-Green battle.
Nevertheless, Labour and the Greens are likely to receive particular attention because of the political positioning of the two candidates.
Abdi-Wali is the leader of Camden Council and has represented Camden Square since 2022. Labour has highlighted her local government experience and work on housing, energy efficiency and community services.
Polanski, meanwhile, is fighting as both Green Party leader and parliamentary candidate.
That creates a dual political test.
The Greens are seeking to demonstrate that their increased support can translate into parliamentary representation, while Polanski is attempting to show that the party can challenge Labour in an urban constituency where left-of-centre voters have several alternatives.
The 2024 result provides important context
Holborn and St Pancras is not an ordinary parliamentary contest.
Starmer won the seat in 2024 with 48.9 per cent of the vote and a majority of 11,572, according to constituency-level election data. The Greens received 10.4 per cent, while independent candidate Andrew Feinstein won 18.9 per cent. Feinstein has since decided not to contest the by-election and has endorsed Polanski.
That previous result is important because the independent vote represented a substantial share of the electorate.
It means that comparing the upcoming contest directly with a conventional Labour-Green contest would overlook the unusual political circumstances of the 2024 election.
Reuters also reported that Polanski’s selection was taking place against the background of the 2024 result, when the Green Party exceeded 10 per cent in the constituency and a prominent independent candidate opposed to Israel’s actions in Gaza attracted a significant vote.
The absence of that independent candidate creates a different electoral environment in 2026.
Whether those voters move towards the Greens, Labour, another candidate or choose not to vote will only become clear once ballots are counted.
National polling shows a more complicated picture
The council defeats have also arrived as the Greens’ national polling position has changed from its earlier peak.
The latest YouGov Westminster voting-intention poll, conducted on September 13–14, put Labour and Reform UK both on 23 per cent, with the Conservatives on 20 per cent. The Liberal Democrats were on 13 per cent and the Greens on 11 per cent.
YouGov said the Greens’ 11 per cent was their lowest figure in its tracker since September 2025 and ten points below their March peak.
That represents a measurable decline in the YouGov series.
But it is important not to turn one poll into a definitive statement about the electorate. Polls measure voting intention at a particular point in time and carry sampling and methodological uncertainty. They also measure Westminster voting intention rather than the preferences of voters in one London constituency.
Earlier YouGov surveys illustrate the movement. The Greens were on 13 per cent in the August 23–24 poll and 12 per cent on September 6–7 before reaching 11 per cent in the latest survey.
That sequence provides evidence of a recent decline within this particular polling series, but it does not establish what will happen in Holborn and St Pancras.
The Greens face competition from both directions
One of the challenges for the Green Party is that its potential support comes from different groups of voters with different priorities.
Some voters may be attracted primarily by environmental policies, while others may be interested in housing, wealth distribution, public services or foreign policy.
That creates opportunities for the Greens but also exposes them to competition.
Labour can compete for voters who prioritise public services, redistribution and progressive social policies while wanting to support the governing party.
The Conservatives and Reform UK occupy a very different part of the political spectrum but can compete for voters who are dissatisfied with environmental policies they consider costly or restrictive.
The two council by-election results illustrate this geographical and political challenge.
In Walkley, Labour was able to recover a Green-held seat. In Wreake Valley, the Conservatives won while Reform finished second and the Greens fell to third.
Those outcomes do not point in a single ideological direction.
Instead, they demonstrate that the Greens are competing in different political environments, with different parties capable of challenging them depending on the constituency.
Polanski’s leadership is under scrutiny
The results also inevitably place attention on Polanski’s leadership.
He became Green Party leader during a period in which the party’s national polling support increased sharply. His political message has emphasised wealth inequality, stronger environmental action, public ownership and policies intended to distinguish the Greens from Labour.
The Holborn and St Pancras campaign therefore offers an opportunity to test whether that message can attract voters in a constituency with a large and diverse electorate.
But there are also organisational pressures.
The Green Party executive recently rejected a request to postpone its annual conference so that campaign resources could be concentrated on the by-election. The conference is scheduled to begin in Brighton on October 2 and finish only four days before polling day.
The timing has generated discussion inside the party about how resources should be divided between national party business and the parliamentary contest.
It is not evidence by itself of a leadership crisis, but it highlights the logistical demands facing a party attempting to expand its parliamentary presence while simultaneously managing its national organisation.
A test of whether Green momentum can be sustained
The two council defeats therefore arrive at a significant moment.
For the Greens, the immediate challenge is to prevent local setbacks from becoming a wider narrative about declining momentum.
For Labour, the Sheffield result provides evidence that it can compete directly with the Greens in at least some urban areas.
For the Conservatives, the Wreake Valley result demonstrates that the party can still win local contests where the Greens and Reform are also competing.
And for Reform UK, the results offer another indication that it can remain competitive outside its strongest areas.
But none of those conclusions should be extended beyond the evidence.
A council by-election involving a few thousand voters is not equivalent to a national general election. Nor can Westminster polling determine the outcome of a specific constituency contest.
The more immediate question will be what happens in Holborn and St Pancras.
Fifteen candidates are on the ballot, and the electorate will decide whether the next MP is Labour, Green, Reform, Conservative, Liberal Democrat, Workers Party or another candidate.
For Polanski, the contest will provide a highly visible test of whether the Greens can convert their recent national growth into a parliamentary breakthrough.
For Labour, it will test whether the party can retain support in a constituency that has traditionally been strongly Labour but whose political landscape has changed since the 2024 election.
And for voters, the choice involves several competing political programmes rather than a simple two-party contest.
The two council by-election defeats have certainly given the Greens an uncomfortable headline.
The more consequential question, however, will be whether those results remain isolated local contests — or whether they form part of a broader change in the party’s electoral position.
That will be measured not by one night’s results, but by the votes cast across multiple constituencies and elections over the months and years ahead.