For Zack Polanski, the Holborn and St Pancras byelection is being presented as a contest that could redraw Britain’s political map — but he insists it is not a referendum on his leadership.
With the vote scheduled for 8 October, Polanski describes the race as effectively level: a “50/50” contest balanced on a knife edge. He wants Keir Starmer’s former seat, but says losing it would not threaten his position as Green leader.
That confidence matters because the Greens have spent the past year trying to turn rising membership and polling support into something much harder to manufacture: votes on the ground.
A leader caught between two battles
Polanski’s challenge is unusual. He is simultaneously campaigning to become an MP while insisting that he does not need parliamentary office to lead his party.
He argues there are advantages to remaining outside Westminster, although entering parliament would give him another platform from which to challenge the Labour government.
Yet the pressure around the byelection is visible. Polanski previously sought to postpone the Green Party’s annual conference so resources could be concentrated on Holborn and St Pancras. The party executive rejected the proposal, with thousands of members expected at the Brighton conference only days before polling day.
That episode exposed a wider tension: Can a rapidly expanding political movement convert enthusiasm into disciplined electoral machinery?
Then there is Andy Burnham
The contest is also becoming a test for Labour’s new direction under Andy Burnham.
Polanski argues that Labour risks losing progressive voters if its promises on climate, living costs and social justice do not translate into immediate action. He has particularly targeted the government’s position on North Sea oil and gas, including the Rosebank and Jackdaw projects.
The timing is politically significant. Reporting indicates that the Jackdaw decision is expected to come after the byelection, while Rosebank remains pending.
For Polanski, this creates a simple political argument: if Labour talks about change but delays difficult decisions, voters may look elsewhere.
Labour, meanwhile, has selected Camden council leader Sagal Abdi-Wali, a former child refugee from Somalia, to contest Starmer’s old constituency.
Gaza, identity and an increasingly difficult internal debate
The election is unfolding alongside a significant internal argument within the Greens.
At the party conference, members debated a motion declaring “Zionism is racism”. Former Green leader Caroline Lucas, former co-leader Adrian Ramsay and co-deputy leader Rachel Millward have distanced themselves from the proposal, warning that it could be divisive. Some Jewish Green members have also expressed concern about its implications.
Polanski says the issue is not his priority, instead highlighting the cost of living, public ownership of Thames Water and the war in Gaza. The controversy nevertheless places his leadership under another spotlight at precisely the moment his party is trying to demonstrate electoral momentum.
From climate politics to the price of rent
Polanski has also attempted to broaden the Green message beyond environmental politics.
At the Brighton conference, he proposed a three-year emergency brake on private rents, with increases limited to the lower of CPI, wage growth or 2%, alongside protections against evictions disguised as rent rises.
It is a deliberate attempt to make the Green pitch about something voters encounter every month: the cost of keeping a roof over their heads.
And that may ultimately be the deeper story of Holborn and St Pancras.
This is not simply Polanski versus Labour.
It is a test of whether the Greens’ recent expansion can survive contact with a real constituency, whether Labour can reconnect with voters who have moved towards the Greens, and whether national arguments about climate, Gaza, housing and living costs can be translated into votes on one London ballot paper.
Polanski says his leadership does not depend on the result.
But the result will inevitably provide another piece of evidence about where the Green Party stands in Britain’s rapidly changing political landscape.
