Zack Polanski, leader of the Green Party, called on voters to support the Greens as a means to push the Labour Party further to the left on a range of issues, including rent controls, wealth taxation, fossil fuels, and the conflict in Gaza. Speaking at the Green Party conference in Brighton, Polanski framed backing the Greens as the most effective way to influence Labour’s policies, particularly aiming to halt a recent shift of left-wing voters from the Greens to Labour under new Labour leader Andy Burnham.

Polanski highlighted several policy proposals advanced by the Greens amid their recent surge in public support. These include a three-year emergency freeze on private rent increases, plans to tax extreme wealth, and a pledge to end new oil and gas drilling in the North Sea. His address focused heavily on the upcoming Holborn and St Pancras by-election, where he is standing as the Green Party candidate and hopes to defeat Labour’s nominee. After delivering his speech, Polanski chose to concentrate on campaigning locally rather than remain at the conference.

The Brighton event drew approximately 3,200 members, with about two-thirds of a hall filled for Polanski’s keynote. The party has seen a rapid rise in membership since Polanski became leader last autumn, reportedly increasing from 70,000 to over 220,000 members. This growth coincided with the fragmentation of the left following disagreements within Labour and the emergence of new factions like Jeremy Corbyn’s Your Party, prompting many left-wing activists to shift toward the Greens.

Within the party, this influx of newer members has led to a notable transformation. Whereas the Greens were once associated primarily with environmentally focused, moderate supporters, the party now includes a significant contingent of more radical left-wing activists. Issues such as Palestine activism, immigration, and social justice have taken on heightened prominence, sometimes overshadowing traditional ecological concerns. At Brighton, the atmosphere reflected this shift, with visible expressions of identity politics and leftist solidarity including symbols linked to Palestine.

Polanski, a former Lib Dem and Labour supporter who became a London Assembly member in 2021 before ascending to party leadership, is a divisive figure. His background includes claims from critics that his rhetorical style is theatrical and sometimes incoherent, with some viewing him as a polarizing force within both the Greens and broader British politics. While his leadership has energized the party’s base and expanded its membership, it has also stirred internal tensions and questions about the party’s direction and electoral prospects.

The Holborn and St Pancras by-election next week is seen as a critical test for Polanski and the Greens. Some observers suggest that a defeat could undermine his leadership position, while supporters argue that continued Green momentum could reshape left-wing politics in the UK by compelling Labour to adopt more progressive policies. The debate over the party’s future course, including contentious proposals such as declaring Zionism a form of racism, reflects broader struggles within the Greens between traditional environmentalism and a more explicitly radical left-wing agenda.