Keir Starmer abandoned net zero to court Reform voters. He failed | Keir Starmer

Less than a year ago, Keir Starmer declared before an audience of senior officials and business leaders from 60 countries in London that climate action was “in the DNA of my government”.

His Lancaster House speech, which promised to reach net zero and “accelerate” while others slow down, was his strongest intervention on the issue yet. “We are paying the price for our overexposure to the ups and downs of international fossil fuel markets,” he said. “Home-grown clean energy is the only way to take back control of our energy system.”

For many who know Starmer, this speech reflected his genuine and rationally considered view. Climate action is not only necessary, it is also economically beneficial and could help the UK avoid future cost-of-living crises; claims he makes in both private and public spheres.

But throughout his premiership, Downing Street has also hosted senior advisers who are skeptical of green issues. They have tried to suppress Starmer’s pro-climate interventions, watered down environmental policy and tried to steer Labor towards Reform and the Conservatives’ anti-net-zero stances.

This group has now seen the consequences of their actions. Labour’s safe seat of Gorton and Denton has moved decisively towards the Greens. Labour’s devastating campaign left it vulnerable and its messages confusing: Reform targeted Labor but the Greens triumphed with a message of hope, faith in public services and strong environmental action.

Starmer now faces renewed questions over his leadership. The Greens face tough choices as they take their first byelection seat. Will he reassert his pro-climate instincts? Is there enough time to abandon the anti-green advice that has brought it to this point?

Greenpeace UK head of politics Ami McCarthy said Labor needed to urgently seek a reset. They said: “Gorton and Denton’s message to Westminster is loud and clear: people are hungry for change. This is a victory for people’s power over billionaires and big polluters, for the politics of hope over the politics of hate, for kindness over denial and division.”

“Parties committed to tackling the climate crisis received twice as many votes as Reform, demonstrating the limited public appeal of Nigel Farage’s climate-denying, renewable-hating, Trump-loving platform. And there’s a clear lesson for Labor here too: if they want to gain power from the Greens, they need to deliver the bold solutions on cost of living, climate and nature that people are clearly looking for.”

Asad Rehman, chief executive of Friends of the Earth, said Labor needed to understand that its cost-of-living policies had to be presented from a pro-net-zero perspective because that was how voters saw them. He said: “As the elections approach, people [said] Making their homes warmer to reduce their bills, improving public transport, improving green spaces and strengthening local communities are among their top priorities.

“We need politicians pushing for affordable and achievable green policies, like increasing renewable energy sources and making polluters pay to take action to combat the climate crisis they cause.”

So how did Labor get it so wrong? The recent history of Starmer’s green agenda reveals how the prime minister has been overtaken by charismatic Green leader Zack Polanski. According to those in Downing Street, the speech at Lancaster House last April should not have happened; Messages about “net zero” being in Labour’s DNA were contrary to the direction they believed the party should go, which was to move increasingly towards Reform. Interestingly, the major announcements that led the press office barely made it onto the news ‘table’ and went largely unreported in the British media.

Less than six months later, in September, the same No 10 operation took a much more active interest in another climate event: the COP30 UN climate summit in Brazil. Starmer told reporters firmly: would not attend. The climate could do without it; he was busy.

These briefings turned out to be false. Starmer went to Cop30, just as he attended Cop29 for the first time as prime minister and Cop28 as leader of the opposition.

But the briefings were no coincidence. They followed months of intense leaks and briefings against energy secretary Ed Miliband and his climate and environment commitments more broadly.

Since Starmer appeared likely to take office, a faction within his government has worked against his green agenda. The most influential figure in this group, the Guardian understands, was the recently departed chief of staff Morgan McSweeney.

McSweeney was one of the architects of the Labor Together movement that emerged in 2015. Opposing Labour’s hard left, whose champion Jeremy Corbyn won the party leadership after Miliband’s general election defeat, Labor Together came from the Blue Labor tradition, and the environment was never a priority for the group.

“This was seen as something for the Liberal Democrats; not a social justice issue, not a hard-fought campaign issue, not in their mind Labour’s core issue,” one observer said. One former campaigner added: “Labour was for the urban; the countryside was for the Tories.”

McSweeney also developed links with Peter Mandelson and Labor’s most electorally successful prime minister, Tony Blair, which appears to have contributed to his resignation. Mandelson’s consulting firm, Global Counsel, counts BP and Shell among its clients. Blair, whose think tank is funded and advised by petrostates, attacked aspects of net zero policy last year, declaring that “any strategy based on short-term ‘phasing out’ of fossil fuels or limiting consumption is a strategy doomed to fail.”

McSweeney was instrumental in downgrading Labour’s key pre-election pledge in 2021 to spend £28bn a year investing in the UK’s green economy. This has been reduced to a spending commitment of roughly half as much, less than six months before the general election.

But Starmer drew his own views from a wider range of sources, including McSweeney and Labor Together, as well as Miliband, economists and business leaders; These argued that the UK would benefit from pursuing policies that support a green transition. Rachel Reeves followed suit, declaring she would be the “first green chancellor” in 2021.

Despite this, Starmer’s record on climate is generally positive, according to campaigners. McCarthy said: “He deserves huge credit for making the bold clean energy 2030 target one of the government’s core missions. We have seen record-breaking auctions for renewable energy and delivered new solar power at half the price of new gas. Along with new incentives for heat pumps and insulation, this plan could deliver lower energy bills and green jobs while reducing our dependence on gas markets dominated by dictators like Putin.”

It is harder to find praise for nature conservation. Attacks on “bats and salamanders” as obstacles to development and the loosening of basic protections have raised questions about Trump’s decision in a country where voters pride themselves on their love of animals.

Shaun Spiers, of the Green Alliance think tank, said: “The Prime Minister was wrong to pit growth against nature, and the chancellor is wrong to continue to do so. It is tragic that Starmer’s government has sourced so much of its planning policy from opaquely funded right-wing campaign groups and think tanks.”

Now that McSweeney is gone, it’s up to Starmer to decide whether to follow his own instincts or the impulses of other interests. Although some sections of the media are keen to highlight any wavering in public support for net zero, support remains fairly resilient. Research conducted by King’s College London in February It found that roughly two-thirds of British people want the government to reach net zero by 2050 or earlier.

Labor is losing more voters to the Green party and Liberal Democrats than to Nigel Farage, according to the latest YouGov poll, a trend supported by the Manchester by-election. The memory of the rise in energy prices following the war in Ukraine remains fresh, and the promise of clean, green, home-grown energy to replace volatile imported gas remains attractive.

Robbie MacPherson, a Kennedy scholar at Harvard University and former head of the secretariat of the parliament’s all-party climate group, said the whole party – Starmer and his potential rivals – needed to take notice, return to Starmer’s instincts and adopt Labour’s “DNA” on reaching net zero and tackling the cost of living.

He said: “Delivering and building on the ambition set out in Labour’s 2024 manifesto must be the priority of every elected Labor politician – it is the best way to retain power and defeat the Reformation.”