Louise Thompson, University of Manchester

The byelection in Gorton and Denton this week has been huge for the Green party of England and Wales, with Hannah Spencer pushing Reform’s Matt Goodwin into second place, and Labour into third. Having one extra MP in parliament may not seem like a big milestone, but this byelection win is record-breaking for the Greens. I believe it shows their potential to be a credible alternative to Labour.

The Greens had never won a byelection before. They polled less than 7% of the vote (coming in fourth place) in the Runcorn and Helsby byelection in May 2025. And, unlike Reform UK in that byelection, the Greens didn’t just edge this victory – they took nearly 41% of the vote. That’s a whopping 28-point increase on their performance in the same constituency at the 2024 general election.

The victory has given party leader Zack Polanski the confidence that voters now see the Greens as a viable alternative to Labour, even in former Labour strongholds. He announced to supporters, “this is what replacing Labour looks like”.

Over the past few years the Greens have really professionalised their party. We saw the impact of this in the 2024 general election, when they quadrupled their number of MPs and finished second in 40 constituencies.

Under Polanski’s leadership, they’ve developed a more populist edge, focusing on issues such as the cost of living and moving away from being “just” a climate party. They’ve also had a more visible media presence and started to take their communication strategy more seriously.

Spencer’s win increases the size of the Green parliamentary group to five MPs. In the context of a 650-member House of Commons, this doesn’t seem like much.

The Greens certainly aren’t large enough to swing any votes, or cause the government many problems. And although they now have more MPs than ever before, they are still only the sixth-largest party group in the Commons. There are still over twice as many independent MPs as there are Greens.

The win will, however, give the Greens some breathing space. It’s a tough job being a small party in the Commons, and the existing group of four Green MPs have shared a heavy burden of responsibilities in the chamber since their arrival in 2024. As Spencer finds her feet, she will be able to take on some of these policy portfolio responsibilities.

Having a bigger parliamentary team doesn’t just alleviate some of the pressure to be in the chamber all the time. It also allows the party to be more strategic, and to insert Green voices into more conversations than before.

This could be through places on committees scrutinising legislation, trying to catch the speaker’s eye during high-profile government statements and question times, or holding backbench debates on more local issues. There is no place for passengers in any small party, so we can expect to see Spencer playing a very visible role for the rest of the parliament.

The battle ahead

When the next general election draws closer, the Greens may be grateful of this bigger team. They will want to capitalise on their success in Manchester and continue to professionalise their operations as a national party.

They are also likely to face more hostility at Westminster. Labour is now fighting a war on two fronts. The party’s embarrassing third-place result in Gorton and Denton – which Keir Starmer called “very disappointing” – will have hammered this home. We can expect to see more attacks on the Greens, including in the Commons chamber.

Until now, the prime minister has focused much more consistent attention on discrediting Reform. Now, he needs to worry much more about Polanski and the Greens, and will be directing some focus to winning back Labour voters who see the Greens as the stronger party of the left.

We had a glimpse of this in January, when North Herefordshire’s Ellie Chowns used her occasional opportunity to question the prime minister to ask about water pollution. Starmer turned it into a partisan attack on the unrelated topic of Polanski’s comments about Nato.

While the Reform UK leader, Nigel Farage, regularly berates Starmer in the Commons, the Greens rarely take such an overtly partisan approach. Reform MPs tend to participate more frequently in high-profile parliamentary occasions, where they can question the government. The Greens tend to have a more balanced, policy-focused approach, regularly popping up on committees to scrutinise legislation.

This is helped by Polanski’s position as a leader who sits outside the Commons (a member of the London Assembly). He can delegate the scrutiny of government policy to Chowns and her colleagues, while he takes broader comments about the government’s performance directly to the press.

This balance will be important as the Greens think about the upcoming local elections. Spencer told the press today that the party can now “win anywhere”, and Polanski predicted a “tidal wave” of Green MPs at the next election.

To do this, they need to maintain the momentum they’ve created this week. This means keeping a tight hold of the former Labour voters who chose them instead in Gorton and Denton.

It will be difficult for the party to carry out the same intensive campaign strategy on a more national level, but this sort of intensity is key to ensuring that the left vote goes to the Greens rather than to the other alternatives. Having more party members than ever before will help with this, but they will need to rely on their on-the-ground campaigners to feel secure.

Louise Thompson, Senior Lecturer in Politics, University of Manchester

This article is republished from The Conversation under a Creative Commons license. Read the original article.

dizzy: I won hundreds of pounds by gambling on this election. I have a bet on the Green party at general election at 66/1.