Zack Polanski wins Green Party leadership in 84.6% landslide, ending co-leadership era

• by Arlen Fitzpatrick
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Zack Polanski has taken the helm of the Green Party of England and Wales with a crushing mandate, winning 84.6% of votes in a leadership election that will reshape the party’s style and strategy. The result was announced just after 11am on Tuesday, September 2, 2025, at a community centre in Waterloo, London.

The London Assembly member and former deputy leader scored 20,411 votes, swamping the joint-ticket challenge from MPs Adrian Ramsay and Ellie Chowns, who together polled 3,705 votes (15.4%). In total, 24,265 members cast ballots. The size of the win ends the Greens’ recent run of co-leadership and signals a clear appetite among members for a more aggressive, populist-tinged approach aimed at breaking out of the party’s traditional lanes.

Polanski campaigned on what he called “eco-populism,” a promise to fuse climate urgency with a bolder communications style designed to reach people far beyond the usual green enclaves. He talked about “substance with clickbait,” the idea that serious policy can travel further if packaged with memorable storytelling and sharper, more frequent messaging.

What the result says

On raw numbers, the outcome wasn’t close. The Greens put the result out in full: 20,411 for Polanski, 3,705 for Ramsay and Chowns, with 24,265 voting. That scale matters. It gives Polanski political room to move quickly on his plans—and puts pressure on internal critics to work with, not against, the new direction.

The contest ran from June 2 to August 30 and was described inside the party as fierce. Ramsay and Chowns framed their run as continuity after a breakthrough general election in 2024, when the Greens won four Westminster seats under the joint leadership of Adrian Ramsay and Carla Denyer. Their pitch leaned on steady growth, a sharp local focus, and courting a broad coalition that included disillusioned Conservatives in rural and suburban areas. Both Ramsay and Chowns now sit in Parliament—proof their model can win under first-past-the-post in the right places.

Polanski offered a different bet: unlock rapid visibility and scale. He argued that the party’s values are popular but under-amplified, and that the Greens have too often looked careful when the political moment rewards clarity and emotion. That contrast—movement-building versus steady consolidation—defined the race.

There were headwinds. Polanski only joined the Greens in 2017 after leaving the Liberal Democrats, a switch that some members still question. His past work in hypnotherapy also drew scrutiny during the campaign. But those lines of attack didn’t land hard enough to dent his momentum, helped by endorsements and attention from figures associated with the Corbyn-era left, including former Jeremy Corbyn spokesperson Matt Zarb-Cousin and writer Grace Blakeley.

That support brought energy—and controversy. Some senior Greens privately bristled at what they saw as an influx of new, left-leaning members, with one describing the mood around the campaign as akin to a “hostile takeover.” Polanski’s camp saw it differently: a sign the party can grow fast if it speaks with confidence to voters frustrated with the political status quo.

On stage after his win, Polanski made a unity pitch. He pledged to “work every single day” for environmental, social, racial and economic justice, and told those who didn’t back him that disagreement is part of a healthy democratic party—as long as there’s “common cause.” The line was aimed squarely at healing internal divides and keeping the focus outward.

Where Polanski wants to take the Greens

Expect a noisier, more online Green Party. Polanski has promised a mass-membership movement that can set the agenda, not just react to it. That means more video, more rapid response, and more emphasis on framing Green policies through stories that land in people’s feeds and conversations. The policy core won’t change—climate action, social justice, and clean, affordable energy—but the packaging will.

He also wants to differentiate the Greens clearly from both Labour and Reform UK. From Labour, he argues, the Greens will offer bolder climate targets, stronger guarantees on living standards, and a more forthright stance on public services. Against Reform UK, he is likely to counter culture-war politics with a pitch rooted in fairness, community, and the costs of environmental delay. He calls it a more “bombastic” communication style from the left—one that uses simple language without dumbing down the substance.

The Waterloo announcement capped a campaign that felt more like a movement launch than a standard leadership bid. Polanski’s team leaned into digital reach and volunteer energy, betting that visibility drives membership, membership drives money and organization, and organization wins seats. The Green Party’s challenge, as always, is converting national support into wins under first-past-the-post—where a few thousand votes, concentrated in the right wards and constituencies, matter far more than broad but shallow popularity.

That’s where the strategic debate now moves. Ramsay and Chowns personify the localist, target-seat grind that delivered 2024 breakthroughs. Polanski isn’t rejecting that; he’s arguing it needs a louder national platform to fuel it. The risk is obvious: get the tone wrong, and the party’s painstaking local work could be drowned out by national noise. Get it right, and the Greens could turn episodic surges into durable clout.

Polanski’s CV gives him a base to start from. He has been on the London Assembly since 2021 and served as deputy leader since 2022, giving him on-camera experience and a national profile that many Greens outside Westminster lack. He also knows the perils of message discipline in a crowded, combative media environment—especially when his opponents will try to paint “eco-populism” as style over substance.

What might change quickly? Expect a tighter central comms operation; more training and toolkits for local parties to localize national messages; and coordinated campaigns that tie climate to everyday costs—energy bills, home insulation, buses and trains, clean air, and jobs in green industry. Polanski is likely to push for more relatable framing: not “net zero by year X,” but “your bills down this winter,” and “kids breathing cleaner air on the school run.”

Internal politics will matter, too. Ending the co-leadership era is more than a personnel change; it’s a cultural shift. For years, the Greens pitched themselves as collaborative and pluralistic at the top. A single leader can be faster and clearer, but it also means sharper accountability and a higher ceiling for personal brand risk. Polanski’s huge mandate gives him authority—now he has to keep the party’s many tendencies rowing in roughly the same direction.

The next tests will come fast. Local elections never stop, and any by-elections will be an early read on whether the new tone is reaching beyond the base. In Wales and across English councils, the party will want to show that a bigger national voice makes canvassing doors easier to open, not harder. Candidate selection, discipline, and message consistency will be under the microscope.

For voters, the question is simple: do the Greens feel closer to their lives? Polanski is betting that sharper language and bigger reach can get more people to hear policies they already tend to like when they’re spelled out. For party activists, the calculation is different: can a more forceful style build rather than bruise the coalition that’s been growing seat by seat?

Back in Waterloo, the message was unity. Polanski knows he has to bring skeptics with him while keeping the energy from his supporters. If he can keep that balance—movement energy plus electoral discipline—the Greens may find they’ve picked not just a new leader, but a new way of doing politics.

• Result: 20,411 votes (84.6%) for Polanski; 3,705 (15.4%) for Ramsay/Chowns
• Turnout: 24,265 members
• Announcement: 11am, September 2, 2025, Waterloo, London
• Backdrop: Greens won four Westminster seats at the 2024 general election