Seahorse insight: what Gorton and Denton tells us

By Matthew Dawson, Senior Account Manager, and Jade Pallister, Director, Energy & Infrastructure

The Seahorse team were on the ground in Manchester ahead of last night’s bombshell result in Gorton and Denton. 

For those engaged in public affairs, it is always wise to exercise caution when interpreting a by-election result.  

The Conservatives’ Uxbridge by-election win in July 2023 is a case in point. Essentially a ULEZ referendum, the result was interpreted as proof that net zero was electorally toxic, prompting Rishi Sunak to dilute key net zero ambitions. What followed speaks for itself.  

However, despite these caveats, there is no doubt that Gorton and Denton will be felt as a watershed moment.  

The Greens won this by-election by a huge margin, their vote surging from 13.2% to 40.6% as Labour’s halved to just 25.4% and it plummeted to third place. 

Reform failed to win and managed expectations poorly in what was always challenging territory. Still, their 28.7% is in line with national polling and represents a 15-point increase on their 2024 result locally. 

The Labour Party put everything into it – it sent its top activists and organisers – Keir Starmer even visited - and the result wasn’t even close. 

It is a loss that will be felt deep within the Party - particularly MPs in the 39 seats across the party’s urban heartlands in London, Manchester, Sheffield and Norwich where Greens came second in 2024. But it will also be felt by the other 372 seats that rely on a united left. 

How did we get here? Since becoming leader in 2020, Keir Starmer pursued a deliberate strategy of professionalising the party and marginalising its activist left. The 2024 operation, spearheaded by Morgan McSweeney, prioritised swing seats (safe seat MPs were punished for campaigning in their own patch) and accepted the risk of alienating traditional voters in urban heartlands.  

That strategy delivered a landslide in 2024 - but traditional Labour seats suffered.  

Even in 2024 in Gorton and Denton, the traditional Labour seat saw a vote share fall of 17% – the Greens up by 15%. After, the left-wing of the party warned that support for Labour was simply an anti-Conservative vote whose voters could be swayed when a better left-leader came along. These were early warning signs.  

Since the failures of the Winter Fuel Allowance and PIP, there have been signs of adjustment. The scrapping of the two-child benefit cap, McSweeney’s departure, the Prime Minister’s recent letter promising cultural change within government and to listen to backbench MPs. The question inside Labour was whether that would be enough to bring back the left. Gorton and Denton has provided an early answer. 

This has consequences for Labour’s governing strategy and any future leadership contest. 

In that environment, leadership hopefuls will be incentivised to move leftwards to reassure members and urban MPs. There will also be those who argue that Reform may be approaching its ceiling and that the more immediate threat now lies on Labour’s left flank. 

The Greens’ victory is therefore significant for environmental politics. Their constitution commits them to implementing ecological policy and their candidate, Hannah Spencer, has been explicit about her commitment to the climate emergency. Yet on the ground, environmental messaging was secondary to cost of living, housing and Gaza.  

By contrast, Reform’s Matt Goodwin argued that high bills and weak growth are linked to net zero and called for it to be slashed. This result will not deter Reform from believing that its regressive energy message resonates. 

In that respect, nothing has changed – Labour will continue to face challenges from both sides, to appeal to the centre and the left. Climate and energy policies will continue to be politicised.  

For those working in renewables and environmental campaigning, that presents opportunity as well as risk. 

It underlines the importance of cross-party engagement mid-cycle and the need for a durable political strategy that can withstand a rapidly shifting electoral landscape.