Zack Polanski, leader of the Green party of England and Wales, is attempting to take Keir Starmer's former seat of Holborn and St Pancras from Labour in a byelection he describes as 'probably 50/50 right now' and 'really on a knife edge.' He insists his leadership does not depend on the outcome. Senior party figures privately believe the opposite — that defeat could severely damage his position. The gap between Polanski's public confidence and internal party anxiety is the real story. The Greens' rapid rise in membership and polling has not, according to internal concerns, translated into ground-level campaigning strength. Polanski's proposal to postpone the party's annual conference to concentrate resources on the byelection was rejected by the executive, exposing friction between the leader's priorities and the party's institutional structures. The byelection carries policy weight beyond party politics. Polanski claims decisions on North Sea drilling projects Rosebank and Jackdaw have been delayed until after the vote, because the government 'literally wants to see whether he can get away with drilling for new North Sea oil and gas.' The Guardian has reported the Jackdaw decision was likely held until after the byelection, while Rosebank remains pending. Both projects already hold licences granted under the Conservatives; Labour approval would not constitute issuing new exploration licences. Polanski frames the contest as a referendum on Labour's climate credibility under Andy Burnham, arguing there is a 'glaring gap' between Burnham's rhetoric and action. He offers two scenarios: either Burnham delivers on his promises — in which case pressure from the Greens worked — or the promises prove hollow and voters migrate further toward the Greens. It is a heads-I-win-tails-you-lose framing that only holds if the Greens can demonstrate electoral viability, which is precisely what this byelection tests. Burnham's challenge is whether Labour can reclaim progressive voters who have drifted Green. Polanski's pitch is direct: 'You don't have to accept the half-fat version.' He attacks Labour on cost of living, wealth inequality, and Palestine, citing arrests of Palestine Action supporters outside Labour conference while Ed Miliband told delegates they were 'right on Palestine.' A separate test awaits at the Green party conference, where members will debate a motion declaring 'Zionism is racism.' Some Jewish members have raised concerns about their place within the party. Polanski downplays the motion, saying 'this motion isn't my priority' and that it has 'absolutely nothing to do with disciplinary action against anyone.' Whether that reassurance holds under the pressure of a contentious floor debate remains to be seen. The structural question is whether the Greens can convert polling gains into seats and governing credibility, or whether they remain a pressure vehicle that moves Labour leftward without ever holding the lever themselves. A loss in Holborn and St Pancras — regardless of what Polanski says publicly — would suggest the latter. A win would force Labour to take the Green threat seriously in every urban progressive constituency.
