It’s early May 2025, another winning day for the Green Party of England and Wales. Hau-Yu Tam, a councillor in the London borough of Lewisham, has just joined the Greens. A photo captures the mood: Tam wears a bright green satin shirt and an even brighter smile. She’s surrounded by other grinning activists, many holding up “Vote Green” signs. To Tam’s right stands then Deputy Leader of the GPEW, Zack Polanski.

Tam is one of a growing number of local councillors who’ve left the UK’s governing Labour Party to join the Greens – a trend that has picked up speed since Polanski was elected leader in early September, with the backing of close to 85 per cent of members.

Almost overnight, the Greens went from a party too often ignored by the media to one dominating the headlines. Polanski’s self-styled “eco-populist” politics and direct communication style have struck a chord across England and Wales. By the end of November, GPEW membership had more than doubled to 180,000, surpassing both the Conservatives and the Liberal Democrats.

Greens are having a moment. But what does this all mean for politics in the UK? And what does it mean for the future of Britain’s relationship to the rest of Europe?

Filling a vacuum

Polanski has been praised for conveying the Green Party’s commitment to tackling inequality and injustice in ways that resonate with a population increasingly anxious over the cost of living and the rise of the far right. In this, he is the latest in a long line of progressive Green activists and politicians. Since its emergence out of the Ecology Party in 1985, the GPEW has gradually shed its reputation as a single-issue party, taking on a platform that grounds environmentalism within the wider struggle for economic and social justice.

Journalist and long-time Green member Adam Ramsay recently charted this journey in an essay for Novara Media. Ramsay credits former leaders Caroline Lucas (also the GPEW’s first Member of Parliament between 2010 and 2024), Natalie Bennett, and Siân Berry for helping to lay “the foundation of the current surge” in Green popularity.

I asked Jeremy Gilbert, Professor of Cultural and Political Theory at the University of East London, why this surge has come now. He puts it in the context of the wider political and economic developments since the financial crisis of 2008. “There’s been a big vacuum in British politics … for at least fifteen years,” Gilbert says. “And that is a space that needed to be occupied by somebody who could articulate publicly a fairly standard … social-democratic position framed in populist terms.”

A decade ago, the Labour Party under Jeremy Corbyn tried to fill that political vacuum. The project was dashed when the Conservatives won the 2017 general election, and Corbyn subsequently lost the Labour leadership to now Prime Minister Keir Starmer. The collapse of Corbynism left an electoral hole on the left. According to Gilbert, “A lot of people, especially young people, who had been active in the Labour Party under Corbyn, went into the Green Party quite quickly, once Corbyn lost the leadership”.

This exodus has picked up speed since Labour won the general election of July 2024, with Labour members, including a number of local councillors like Tam, becoming increasingly disillusioned with the shift to the right under Starmer on issues such as migration, child poverty, climate change, and Palestine.

Battles that unite

Inside the GPEW, grassroots members have been working to make the most of the popular demand for a party to the left of Labour. At the party conference in September 2024, two months after the record election of four Green MPs (Siân Berry, Ellie Chowns, Carla Denyer, and Adrian Ramsay), a group of members launched Greens Organise. GO calls for “the Green Party to realise both its responsibility and potential by stepping up to the historic opportunity to become the electoral voice of a popular movement”. Independent of the GPEW but made up exclusively of GPEW members, GO now has over a thousand affiliates.

With much media attention focused on the new leader, it’s important to remember that Green Party policy is determined by membership. Rather than a change in the party’s direction under Polanski, we’re seeing a shift in emphasis and tone. Tackling the cost of living crisis was already the top item in the GPEW’s 2024 general election manifesto, which committed the Greens to building a “fairer and greener society” in areas such as housing, income, healthcare, education, and nature. Polanski takes up these promises and points the finger at those who are to blame for the injustices. Under his leadership, the manifesto’s call for a wealth tax (1 per cent annually on assets above 10 million pounds, and 2 per cent on assets worth one billion pounds or more) has become the party’s signature policy.

As left-wing journalist Owen Jones puts it, prioritising the message that the rich should pay more tax highlights Polanski’s strategy to “focus on battles that unite (…) without yielding an inch on minority rights”. Polanski has been deft at dodging attempts to drag him into the culture wars. As right-wing pundits accuse him of not knowing what a woman is or “advocating that children be allowed to take” drugs, he defends the Greens’ commitment to trans rights and drug-law reform while reminding his audience that these smears divert attention from what really scares the establishment: the GPEW’s economic policy. The surest sign that Polanski’s tactics are working is the angry headlines in the right-wing press, calling proposals to tax wealth and nationalise utility industries “insane” and “fantasy” economics, and even “fake news”.

Prioritising the message that the rich should pay more tax highlights Polanski’s strategy to ‘focus on battles that unite (…) without yielding an inch on minority rights’.

Freedom of movement

As important as holding the powerful to account is the message about who is not responsible for social and economic inequality. Polanski regularly reiterates that Greens welcome migrants and refugees, emphasising their importance to the country’s economy and cultural diversity. But migration is not his main talking point.

Migration is a line in the sand between the Greens and both Labour and the far-right Reform UK, which is currently leading the polls. Reform UK’s leader Nigel Farage, who rose to fame heading the Brexit Party, has made a career of blaming migrants for Britain’s problems. Polanski is often compared to Farage in terms of style. In Jones’s words, the Green leader, “has embraced the Nigel Farage tactic of confrontation”. But that’s where the resemblance between the two politicians ends. Where Polanski is on record calling the Reform leader a “fascist”, Farage, having successfully campaigned to take Britain out of the European Union, has now turned his sights on removing the UK from the European Convention on Human Rights (ECHR) and the Refugee Convention.

In contrast, international cooperation – in human rights, economics, and climate change – is a pillar of Green policy, in England and Wales as elsewhere. The manifesto for the 2024 elections promises that the party will “work towards (re)joining the EU as soon as the domestic political situation is favourable and EU member states are willing” – a pledge reaffirmed by members at the party’s 2024 conference.

A YouGov poll conducted in June 2025 – nine years after the Brexit referendum – found that 61 per cent of respondents believed Brexit has been more a failure than a success. But the same poll indicates that most people do not consider rejoining the EU a priority. For now, Polanski is focusing on ways the GPEW can strengthen ties to the EU in the shorter term, including rejoining the customs union. In a recent interview with POLITICO, he called the end of free movement between the UK and the EU a “disaster” that should be reversed as soon as possible.

I asked Gilbert whether a commitment to reinstating freedom of movement was likely to be a problem for the Greens, given that in a recent public opinion poll, almost half of respondents cited immigration as the country’s biggest challenge. He observed that the Greens’ target voters – “a progressive and mainly metropolitan vote” – are those who are likely to be in favour of freedom of movement.

When asked by one journalist recently how he will attract a different group or voters – those who agree with the Greens on the economy but not on migration – Polanski again emphasised unity over division, committing to concrete measures to solve the housing shortage or protect the National Health Service, instead of citing migration as the source of those problems.

Electoral prospects

The next big electoral test for the GPEW will come in May 2026, with local elections in much of England, including London. At the party’s conference in October 2025, Polanski announced that the Greens aim to gain “hundreds of new councillors”, as well as their first local mayor in the London Borough of Hackney. They also have their eyes on their first seat in the Welsh Senedd elections the same month.

At the national level, the GPEW’s aim for the next General Election (in 2029 or earlier), is to “hold the balance of power”. As of early November, the specific target was to win 30-40 seats, but if the party’s fortunes continue to rise, that could increase. Recent data suggests the party could gain as many as 50 MPs.

Once in parliament, a top priority will be to push through proportional representation. The party has supported it for years, arguing that the existing first-past-the-post system favours the big parties, disadvantages the smaller ones, and effectively disenfranchises large parts of the electorate. In the 2024 general elections the GPEW got 6.7 per cent of the vote and only 0.6 per cent of parliamentary seats. In contrast, Labour’s 33.7 per cent share of the vote translated to 63.2 per cent of seats.

In the ever-changing panorama of contemporary British politics, one as-yet-unknown entity is Your Party, the new leftwing party founded by Corbyn and another former Labour MP, Zarah Sultana. The party has had a shaky start, with infighting and a chaotic first conference in late November. If it ever gets off the ground, Your Party will be chasing some of the same voters as the Greens, but without the campaign structures the latter has built up over decades.

While Your Party might seek to cooperate with the Green Party in future elections, in Gilbert’s view, “it would make more sense for the Greens to focus on their relationships with Labour and the Liberal Democrats. The Greens historically, and for good reasons, would want to be part of a broad, progressive coalition”. Polanski has stated he will not work with Labour while Starmer is leader, but hasn’t ruled out other pacts. In 2017 then Green co-leader and MP Caroline Lucas proposed a pact to keep the Conservatives out of power, but was rebuffed by both Liberal Democrats and Corbyn’s Labour. The Greens are likely to be in a much better negotiating position at the next general election.

Green parties in Europe have a long history of forming alliances with other parties to get elected or form government. Simon Otjes, Associate Professor of Dutch Politics at Leiden University, has studied the different paths to power among European Green parties. I asked him whether these experiences had any lessons for the Green Party of England and Wales. According to Otjes, the Green parties that have most often helped to form governments are the Finnish and German Greens, both seen today as moderate and “electable parties”.

In Sweden and the Netherlands, Greens have developed successful relationships with left parties. By making pre-electoral pacts with the Social Democrats, the Swedish Greens have had “room for a far more left-wing course”. In the Netherlands, Otjes says the GreenLeft-Labour alliance (set to become a full merger in 2026) “could be said to be a takeover of Labour by the Greens”. He is less certain similar partnerships would work in England and Wales, given that the Greens’ popularity relies on positioning themselves to the left of Labour. 

A diverse movement

One electoral advantage Labour holds over the Greens is its historically high levels of support in Black and brown communities. Over 50 per cent of “ethnic minority” people polled before the 2024 general election said they intended to vote Labour. Green solidarity with migrants and commitment to tackling the cost of living crisis might help to make inroads here. Black, Pakistani, and Bangladeshi households in particular are two to three times more likely than white households to experience “persistent very deep poverty”. There is also evidence, among Muslim voters especially, that the Labour government’s support for Israel has pushed some towards the GPEW, with its consistent pro-ceasefire, anti-genocide stance.

Expanding the Green base also means putting resources into recruiting and training global majority candidates. Hau-Yu Tam, the Lewisham councillor who joined the Greens last year, says this is about “supporting local activists, … showing up for communities on the picket line in protests, in community groups”. These practices and processes are already in place in many local parties. 

Tam speaks from experience. She was born to working-class parents from Hong Kong and raised in a predominantly white area of Kent on the outskirts of London. After joining the Greens, she got involved in Mothin Ali’s campaign for deputy leader of the GPEW. Ali, from a British-Bangladeshi family and also a former Labour Party member, was elected as a Green councillor in Leeds, West Yorkshire, in May 2024. In September 2025 he was chosen as the GPEW deputy leader, alongside Rachel Millward. 

A horticulturalist and longtime anti-racist activist, Ali has been cited as proof that the Greens can move beyond what Tam calls the “by now quite tired stereotype that the Greens are very white, very middle class, very liberal”. Recent data shows that after London, membership numbers are growing fastest in the Northeast of England. Even those who sneer at the Greens from the right are noticing the party gaining ground in Northern England, challenging Reform for support among disgruntled Labour voters and “explod[ing] the myth that the Green revolt is a mere outburst of southern middle-class petulance”.

Even those who sneer at the Greens from the right are noticing the party gaining ground in Northern England.

Keeping the energy up

As anyone who has joined a Green Action Day (a day of campaigning that brings together activists from different local parties) in recent months can tell you, there’s a real buzz in the air. In the run-up to the local elections next May, and onto the next general elections, the challenge will be to keep energy levels up, continuing to turn higher membership numbers into campaigners on the ground.

Polanski insists that current enthusiasm for the Greens “isn’t about me. It’s about growing a team.” Even some of his staunchest supporters have cautioned activists against becoming “obsessed” with the new leader, at the expense of focusing on their own political work. Liam Shrivastava – who, like Tam, crossed the floor from Labour to Green as a Lewisham councillor – wrote recently: “One of left populism’s greatest strengths – for a leader to act as a lightning rod for radical change – is also its biggest weakness. While figureheads are crucial for rallying a constituency of support, they can also have a demobilising effect where supporters become passive cheerleaders”.

Combining strong leadership with an even stronger, active membership is a challenge for any mass democratic party. I asked Tam what her experience had been as a relatively new, and very active, member at a time of such rapid change. “We’re small but mighty and we’re so democratic, I feel very confident that I can help shape that in my own way,” she told me. “So whatever we end up doing as a Green Party, I feel very confident that my voice would be in that strategy, which is a really great thing.”

If the Greens in England and Wales can continue to expand their popular support and membership base and use that base to build a bigger, broader eco-socialist movement, predictions that the party could change the political landscape will be much more than media hype.