Exclusive: Green Party Membership Hits Record High Since Polanski’s Leadership Bid, Leaked Data Suggests

Membership of the Green Party of England and Wales (GPEW) has grown by at least 8% since the party’s deputy leader Zack Polanski launched a leadership bid in early May, figures leaked to Novara Media suggest.

While the party has refused to disclose membership figures during its internal leadership election, projections based on data from regions representing over a third of the party’s membership suggest that the Greens now have at least 65,000 members, up from roughly 60,000 at the start of May. The largest ever Green membership on record was 63,000 in spring 2015.

Responding to the record growth, Polanski told Novara Media: “I’m delighted that so many people are realising the Green party is their political home.”

“The crises facing us are urgent – we don’t have time to waste. I’m delighted to have so much support from the existing membership and our councillors, and to hear that lots of people are joining to vote for me.”

Polanski is taking on the party’s current co-leader Adrian Ramsay, who is now running with his fellow MP Ellie Chowns. His bid has excited the party’s grassroots – in early June, over 100 Green councillors signed an open letter backing Polanski’s leadership bid. Anecdotally, Polanski has cited dozens of instances of people joining the Greens citing his bid as the reason. Ramsay and Chowns, meanwhile, have been endorsed by the former MP and leader Caroline Lucas, and by Green peer Jenny Jones.

There is suspicion among some in the party that parts of the party bureaucracy have blocked publishing membership figures because they know it will highlight what some have described as a “Polanski surge”. Voting in the Green leadership election is open to anyone who joins before 31 July. Voting closes on 30 August, and the results will be announced on 2 September.

While the party’s internal returning officer has banned officers from revealing membership figures during the leadership election, Novara Media contacted representatives of regional and local parties, receiving responses from four that collectively represent roughly a third of the party’s overall membership. Across these, the average membership growth from 3 May (when Polanski launched his campaign) to 19 June was 8%.

In one internal party group chat leaked to Novara Media, a Green party member with access to data from one of the largest regions in England reported that May 2025 showed the second largest membership growth of any month on record, second only to January 2015, when thousands joined the party after then-leader Natalie Bennett was excluded from the national party leaders’ debate in that years’ general election.

In the same group chat, a party member with access to membership data said there had been two recent spikes in new memberships in their region: one after Polanski’s bid, another after Mothin Ali – a Green party councillor in Leeds, who is on the party left – announced his bid for deputy leader.

While some of this surge across the regions seen by Novara Media likely resulted from the party’s successful local elections in May, many activists have put it down to Polanski. Many prominent former Corbynites have publicly declared that they’ve joined in order to back Polanski, including John McDonnell’s former economic adviser James Meadway and the writers Grace Blakeley and Michael Chessum. The prominent internet freedom campaigner Cory Doctorow has also announced that he has joined to back Polanski.

In early June, Novara Media approached the Green press office for updated membership figures (the party’s latest public figures are from March this year). While initially the party’s press officer was enthusiastic, saying the Greens had “passed 60,000” and were approaching the 2015 record of 63,000, they later sent a note declining to offer exact figures, writing, “We’re not going to be publishing our membership figures between now and the leadership election results”.

Asked why it would not publish membership figures during the leadership campaign, the press office replied that “it’s felt that giving membership figures is optional; it is easier to side-step it at this point until the internal elections are done”.

When we put the leaked data to them, the Green party press office said: “We are delighted that local parties are reporting strong growth in numbers. This reflects a continuing upward trajectory in the polls and growing support for our message of real hope and real change.”

Shortly after the party’s membership peak in 2015, thousands of members switched to Labour to back Jeremy Corbyn in Labour’s internal leadership election. By 2018, with leftwing activists continuing to flock to Corbyn’s Labour, Green party membership had fallen to 39,000, before rising steadily, particularly since Starmer took over as Labour leader, reaching 59,000 after the 2024 elections, and 60,000 by March this year. This also means that GPEW has now likely overtaken the Scottish National party as the UK’s fifth biggest party.

The Scottish Greens are an independent party with roughly 7,700 members, making the total number of Greens across Great Britain roughly 73,000.

The Liberal Democrats claim on their website “more than 90,000 members” The Tories had around 130,000 at the time of their leadership election last year. Reform claims to have around 230,000 members, while Labour is believed to have about 300,000, down 11% since the general election last summer.