On January 31st, the Green Party held its largest ever local event in Lewisham. 600 residents gathered to hear deputy leader Zack Polanski speak, an unprecedented turnout for a borough-level event. New and longstanding members came together not just to listen, but to organise: delivering leaflets, knocking on doors and building momentum around the prospect of a breakthrough local victory come May. 

Something that once felt out of reach, had begun to feel possible. 

And it’s not just Lewisham. Across inner London boroughs, from Hackney to Lambeth, Islington to Southwark, the Greens are experiencing a visible surge in energy, membership and confidence. The question increasingly being asked in Labour circles is no longer whether the Greens are growing, but whether that growth is beginning to break down Labour’s traditional urban strong holds. 

Why are they rising? 

There is a clear dissatisfaction of Keir Starmer’s leadership, with many more left-leaning Labour voters looking elsewhere to feel represented in politics. This is most importantly due to Labour stance on Gaza, in addition to climate ambition, renters’ rights and public service investment, all areas where parts of Labour’s base feel unheard, as they look to appear more cautionary. 

Many also point to the short-lived surge of “Your Party”. There was an expectation that left-leaning Labour voters who felt politically adrift would coalesce around Jeremy Corbyn and Zara Sultana’s new movement. But without the early social media mistakes, and early fractures clear between the leadership, that momentum struggled to consolidate. The Greens, by contrast, were already embedded locally, and have been better placed to absorb those voters and represent that demographic. 

Leadership has also been integral. Zack Polanski’s charismatic media presence and bold values-driven campaigning have given the party a clearer public voice. The Greens appear more confident, more disciplined and more electorally focused than in previous London cycles. 

In Lewisham alone, local membership has reportedly multiplied since early 2025, a striking indicator that this is not just passive support, but active mobilisation. 

The impact 

In local elections, where turnout is lower and margins are tight, small shifts matter. If even a fraction of Labour’s traditional coalition of voters in inner London, decide to get behind their Green candidates, previously safe wards can quickly become competitive. 

The Greens do not need to win across the capital to reshape the political conversation. They simply need to demonstrate that Labour’s hold on progressive London is no longer automatic, and this reflects on Labour as a whole and their losing trust with their voters. 

In terms of development, more representation of Green party members on local councils and thereby planning committees too, will mean greater emphasis on their core commitments to sustainability, affordable housing and social value. This is likely to translate into firmer expectations on affordable housing delivery, embodied carbon, urban greening, and scheme quality. 

For developers, this comes at a time when scheme viability is already finely balanced. Additional policy ambition and more rigorous committee-level challenge could prolong negotiations, increase costs, and in some cases delay applications. There is also a risk that some newer Green councillors, less familiar with viability constraints, may push for outcomes that are difficult to deliver in practice, creating further friction and uncertainty in the planning process. 

Not just the greens… 

The fragmentation of London politics is not confined to the left. Reform UK is also seeking to make gains in outer boroughs, appealing to a very different electorate. But while Reform challenges Labour from the right in specific geographies, the Greens operate within Labour’s ideological space. For the first time in many elections, this year’s elections in London will see Labour and Conservative feel more threatened than ever by the rise of the smaller parties, and although we may not see majorities in authorities, we will start to see dominance of either party decline at local level. 

Many Green voters are former Labour supporters. This is not the normal left-versus-right battle, it is a debate about what progressive politics in London should look like to them. 

For Labour, the response will be critical. A stronger policy offer on foreign policy, housing affordability, climate leadership and public services could consolidate wavering voters. But if dissatisfaction persists, and if Green organisation continues to strengthen at local level, May’s elections could mark the beginning of a more competitive progressive landscape.