A Southwark councillor is the latest to ditch Labour for the Greens

Councillor Sam Foster has joined the Green Party and will be its second Southwark Council councillor, alongside Kath Whittam who joined the party in November 2025. This marks yet another defection to the Green Party. They’ve been in touch to tell us more about it.

Foster is part of the “Green Wave” of councillors defecting across the UK. Sam is joining Whittam and a stream of councillors in London who have defected to the Greens in 2025.

Foster said:

The Green Party proposed a radical manifesto at the last general election and in Zack Polanski they have an outspoken, principled leader.

Zack understands the need for a transformation of society in favour of the many and the urgent need to reduce housing costs through measures such as rent controls and mass council house building.

An experienced community activist, Foster has worked on anti-gentrification efforts, eviction resistance campaigns, and mutual aid organising. He represents Southwark’s Aylesbury Estate, which is facing one of the biggest regeneration programmes in Europe.

His focus locally has been on pushing the council to meet its promises to Aylesbury residents and address poor conditions on the estate. He is a committed socialist and trade unionist.

Chaos in Southwark

He left Labour after a ‘summer of chaos’ in the Southwark Labour Party, when their democratically elected leader, primary school teacher James McAsh, was removed by Labour Party HQ, and replaced by property developer lobbyist Sarah King. Local trade unions called this process “an assault on party democracy”.

Describing his resignation from the party, Foster said:

Labour has doubled down on betraying its historic mission as it announced a fascistic policy towards asylum seekers, scrapped jury trials, and watered down its workers’ rights agenda.

The Labour Party has failed us on housing, locally and nationally. Residents on the Aylesbury
Estate have been left in limbo while conditions on the estate deteriorate, and the Council has
spent years failing to address its broken relationship with the development partner Notting Hill
Genesis.

Meanwhile, instead of tackling the housing crisis, this Labour Government is watering
down its affordable housing requirements.

The Greens offer a powerful message of social, economic and ecological justice. While Labour is on the side of landlords and developers, Greens stick up for renters, workers and ordinary people who want to build a better society.

Foster has stood up for residents facing skyrocketing estate heating bills through his work on Southwark Council’s Housing Scrutiny Commission.

He’s opposed developers’ efforts to shirk commitments to build housing in the area around Elephant Park.

And he’s led the Council in supporting low-paid workers at University of the Arts London in their campaign against outsourcing.

Green Party growth

The Green Party’s national membership has grown since September 2025, and now stands at over
170,000, surpassing the reported membership of the Conservative Party and more than double that of the Liberal Democrats. Southwark Green Party membership has quadrupled in 2025.

Kelly Shields, co-chair of the Southwark Green Party, said:

Sam Foster is a committed councillor who cares deeply about the people of Faraday ward and
Southwark.

We are delighted that he has joined the Greens and know he will work hard for residents and fight for their housing rights. He sees exactly how decisions made in Westminster hit lives here in Southwark.

Like many, he knows Labour have misled us, and seeing them in action locally and nationally has shown they have not brought the change they promised.

The Liberal Democrats can’t be trusted. When they had power in Westminster they voted for austerity and higher student fees.

After 14 years in power the Conservatives tanked the economy further, increasing welfare cuts, freezing working-age benefits and introducing the two-child benefit cap.

And Reform threaten our tolerant and multi-cultural society.

People are tired of being let down. They want something better. They want hope. And they know they can find hope here in the Green Party.

Featured image via the Green Party