Green gains: Why eco-populism is reshaping political risk in 2026.

By Isobel Fitzsimons – Senior Account Manager

The growth of the Green Party since late 2025 is not a passing polling story. It is a signal of deeper fragmentation on the British left, and a warning sign for a Labour Government increasingly exposed to pressure from within its own electoral coalition.

Under the leadership of Zack Polanski, the Greens have repositioned themselves from a niche environmental party into a broader eco-populist force. Their polling has risen from below 10% in summer 2025 to consistently around 15%, with peaks as high as 19%. Membership, visibility and confidence have grown in parallel.

Yet their real power lies less in prospects of national Government and more in their ability to unsettle Labour, reshape debate and force behavioural change. The left of British politics is no longer unified. Alongside the Greens sit Corbyn-aligned groupings such as Your Party, and a growing ecosystem of issue-led campaigns focused on Gaza, trans rights, housing and climate. Individually, most lack scale. Collectively, they have weakened Labour’s monopoly on progressive voters and created a volatile environment in which pressure matters more than power.

For businesses and organisations, the risk is not necessarily a Green-led Government. It is policy drift, heightened reputational sensitivity, and a governing party more responsive to activist pressure and local electoral threat. Understanding the Greens now means understanding how influence operates in a fragmented, multi-party political culture.

Polanski describes himself as an eco-populist. His politics fuse environmentalism with inequality, social justice and anti-establishment sentiment. His social media presence is disciplined and deliberately polarising, built around a core question: Who does the system serve? Labour is framed as a replacement target, not simply a disappointment. Momentum itself is the message.

This is already translating into electoral and institutional leverage. In London, all 1,817 council seats across 32 boroughs are up for re-election in May, creating space for Green advances across inner London and the possibility of No Overall Control in multiple authorities. In Wales, the Greens could secure Senedd representation for the first time. In Scotland, the Scottish Greens remain organisationally distinct but are moving closer to their counterparts in England and Wales, reopening formal cooperation.

For brands, developers and regulated sectors, the reputational risk often lies less in formal policy adoption and more in the narratives the Greens legitimise and amplify. Profit, private provision and shareholder value are increasingly framed as extractive. Planning debates are recast around ethics and community control. Infrastructure schemes risk becoming cultural flashpoints rather than technical discussions.

Our new report, Green Gains, examines where the Greens now exert pressure, how their ideas travel beyond formal party politics, and what their rise means for policy, reputation and risk management in 2026.

If your organisation operates in housing, energy, infrastructure, food or regulated markets, this is not a trend to watch from the sidelines.

Download the full report to understand how eco-populism is reshaping the political environment, and what that means for you.