Politics Home Article | Is The Green Party Getting A Wave Of Councillor Defections?

Zack Polanski and Hannah Spencer pose in front of Parliament after Spencer’s by-election victory in Gorton and Denton (Alamy)

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Green sources told The Telegraph last week that around 50 Labour councillors had defected to their party in the past six months, claiming the pace had accelerated as Labour braces for what are expected to be a bruising set of local elections in May.

The sources said the party had been receiving two or three inquiries a week from local Labour politicians considering defecting.

“More and more councillors have been moving to the Greens in the past six months and, like our polling and membership surge, this momentum is increasing,” one source told the newspaper.

The Greens’ victory at last month’s Gorton and Denton by-election underlined the threat that Zack Polanski’s party poses to Labour. Candidate Hannah Spencer won 40 per cent of the vote in a constituency that had been controlled by Labour for over a century.

At the same time, the Greens are enjoying record highs in the national opinion polls.

The Greens certainly have momentum. But when it comes to councillor defections, what do the numbers tell us?

According to the Green Party’s own list of councillors who have joined the party, seen by PoliticsHome, 64 councillors have defected to the Greens since the July 2024 general election at the time of writing.

Of these, 48 defections have taken place since September 2025, shortly after Polanski became party leader on 2 September.

The vast majority of these switches have come from Labour. Fifty-four of the 64 councillors previously represented the Labour Party.

However, the picture is more complicated than a direct Labour-to-Green exodus. At least 10 of those councillors had already left Labour and were sitting as independents before joining the Greens. Several had either been expelled from Labour or deselected ahead of the upcoming council elections.

The Greens currently have more than 900 councillors across England and Wales, up from 859 councillors on 181 councils following the 2025 local elections, when the party made a net gain of 43 seats, its best-ever result.

The party hopes to build on that momentum in this year’s local elections, which are taking place in Scotland, Wales and councils across England. 

In particular, the Greens are seen as a risk to Labour in London, where Polanski has suggested that he could stand to be an MP at the next general election. 

The councillors who have joined the Greens up to now are spread across the country, from London and the South East to Yorkshire and Wales, according to the party’s list.

Tony Travers, professor in local government at the London School of Economics, said the defections to the Greens so far had been “modest in number”.

“They’re not evidence of an exodus from the Labour Party,” he told PoliticsHome.

Travers noted that councillors often defect when they are deselected or politically marginalised, particularly in the run-up to elections.

“They’ve got nothing to lose now by hopping to another party, particularly when that other party might well be more popular than the Labour Party,” he said.

Since the 2024 general election, more than 80 councillors have also defected from the Conservative Party to Reform UK, alongside a handful of defections to Reform from Labour.

“With all the many curiosities of contemporary British politics, one is the fact that Reform and the Greens have a significant amount in common because they’re challenger parties,” Travers said.

“The Greens face exactly the same problem as Reform, which is they’ve got a bit of momentum, but they need to sustain it.”

Polanski recently told The  House magazine that his party was in conversation with a “handful” of Labour MPs considering defecting from Keir Starmer’s party.

“If you speak to some Labour MPs, some days it seems like it’s going to be their last day in the party, and other days they’ve seen a glimmer of light and think everything’s going to be OK,” he said.

Following Labour’s collapse in Gorton and Denton, many Labour MPs urged Starmer to be more progressive in a bid to stop bleeding support to Polanski’s party.

However, multiple Labour MPs told PoliticsHome they were not overly concerned about councillor defections in their own areas, noting that many councillors who joined the Greens had already left the party or been deselected.

Some expressed relief that Labour councillors from the left of the party – or as one MP put it, “troublemakers” – had quit Labour.

There is also concern within the Liberal Democrats that some of their MPs could defect to the Greens amid restlessness over the direction of the party.

A senior Liberal Democrat MP last week told PoliticsHome that at least two Lib Dem MPs — both representing traditionally Conservative constituencies in southern England captured during the party’s 2024 surge – could be tempted to switch to the Greens.

Travers said the Greens were increasingly positioning themselves as a vehicle for political protest.

“They are challenging the Liberal Democrats as a repository for protest,” he said.