The Green Party of England and Wales won four Westminster seats in 2024, the best general election result in its history. The 2024 manifesto was a technocratic system change prospectus: net zero ahead of the legal timetable, £40 billion annual public investment, wealth tax, free social care, decriminalisation, Palestinian recognition. The September 2025 leadership election of Zack Polanski converted that prospectus into a populist movement project. Membership has tripled to over 220,000. The parliamentary footprint has not grown. The gap is between the breadth of policy commitments and the shallowness of the parliamentary base to deliver them.

Under Polanski the manifesto's many revenue measures have been reframed around wealth tax as the central political choice: tax concentrated wealth or accept public service decline. The substance has not changed. The framing has gone from prospectus to argument.

On climate the manifesto's 70 per cent wind by 2030 and £40 billion annual investment was the most ambitious of any 2024 manifesto. The four MP parliamentary group pushes amendments. Labour sets the chamber argument on 2030 clean power with significant chamber time. The Greens have not contested whose version of 2030 is substantive.

On Gaza the manifesto called for immediate Palestinian recognition and end to arms sales to Israel. Labour delivered recognition on 21 September 2025. The arms embargo question remains a Green position parliament has not adopted. Under Polanski the framing has hardened from ceasefire to explicit naming of genocide in Gaza.

On welfare the manifesto pledged £15 per hour minimum wage, Universal Basic Income trial, and scrapping the two child cap. Labour scrapped the cap in November 2025. UBI remains a Green distinctive without a sustained parliamentary campaign.

On housing the manifesto pledged 150,000 new social rented homes per year and rent controls, more ambitious than any other party. The four MP group has not made housing a leading campaign. Rent controls and social housing remain Green positions without Green campaigns.

On the constitution the manifesto committed to proportional representation, voting age 16, an elected second chamber, and written constitution. The party's longest standing argument is for constitutional reform. The Polanski leadership has not made it a campaign priority. The argument has been left to Liberal Democrats and Labour backbenchers, neither of whom has made it either.

The Greens under Polanski have grown membership and narrowed focus to wealth tax, Gaza arms embargo and climate ambition as the leading frame. They have not shown how four MPs and a growing movement convert into the policy power the programme requires. What remains unclear is whether the movement first parliament second model can scale beyond a louder voice in a chamber the four MPs cannot move.