Heathrow Airport's plans to build a third runway have hit severe turbulence after the government confirmed it would not appeal a court decision to block the project on environmental grounds.

The Court of Appeal ruled in favour of green campaigners as part of a wider bid to stop the build by opponents including London Mayor Sadiq Khan and Hillingdon Council.

It found the government hadn't considered its commitments to the Paris Climate Agreement when it backed the scheme in 2018.

Boris Johnson was a vocal critic of the project before he became PM, and transport secretary Grant Shapps has confirmed the government will not appeal the court's decision.

Image: Heathrow wanted to complete its plans by 2029

"Airport expansion is core to boosting global connectivity," Mr Shapps tweeted.


"We also take seriously our commitment to the environment. This govt won't appeal today's judgement given our manifesto makes clear any #Heathrow expansion will be industry led."

Image: Boris Johnson opposed the third runway while London mayor

Heathrow, however, said it would take the case to the Supreme Court and its chief executive John Holland-Kaye told Sky News bluntly: "No Heathrow expansion, no global Britain."

Business groups also expressed disappointment.

But the Court of Appeal judgment was celebrated by victorious campaigners, including Friends of the Earth, outside the court.

Opponents of the runway had argued that former transport Chris Grayling ignored factors such as air quality, noise pollution and traffic congestion when he gave the expansion the go ahead.

Sky News' business correspondent Paul Kelso said Mr Johnson "may be breathing a sigh of relief", as he vowed on several occasions during his time as London mayor to lie down in front of bulldozers to stop work at the site.

Image: Boris Johnson attends an anti-third runway campaign event before becoming PM

He added that the decision could have implications beyond Heathrow, as by citing climate change it had taken the rhetoric of reducing carbon emissions and "turned it into concrete case law".

He said the decision had made reducing climate emissions "a priority for any major infrastructure project" in future.

Will Rundle, head of legal at environmental campaign group Friends Of The Earth, was pleased with that prospect, saying climate change should now be "at the heart of all planning decisions".

He added: "It's time for developers and public authorities to be held to account when it comes to the climate impact of their damaging developments."

Climate activists block roads to Heathrow

But despite the ruling, the judge Lord Justice Lindblom said an expansion has not been ruled out.

He said: "Our decision should be properly understood. We have not decided, and could not decide, that there will be no third runway at Heathrow.

"We have not found that a national policy statement (NPS) supporting this project is necessarily incompatible with the UK's commitment to reducing carbon emissions and mitigating climate change under the Paris Agreement, or with any other policy the government may adopt or international obligation it may undertake.

"The consequence of our decision is that the government will now have the opportunity to reconsider the NPS in accordance with the clear statutory requirements that parliament has imposed."

The judge added that the court's decision was "not concerned with the merits" of a Heathrow expansion, or of doing nothing to increase the UK's aviation capacity.

"Those matters are the government's responsibility and the government's alone," he said.

Image: A third runway at Heathrow was first mooted in 2003

The much-delayed Heathrow expansion plans date back to 2003, when a Labour government White Paper first recommended a third runway was built.

But the project has been mired by political indecision and local opposition ever since, with alternatives having been sought and cast aside during that time.

Businesses had argued it is crucial to the economy as the airport is already operating at full capacity, leaving the UK at risk of being left behind.

Heathrow bosses had hoped to start work on the runway as soon as next year, and most recent estimates had put completion of the new runway at 2029.

Image: Chris Grayling was criticised for not factoring air quality and traffic congestion in the plans

While the government has indicated it will not appeal the ruling, Heathrow has said it will do so.

"We will appeal to the Supreme Court on this one issue and are confident we will be successful," said a statement.

"In the meantime, we are ready to work with the government to fix the issue that the court has raised.

"Heathrow has taken a lead in getting the UK aviation sector to commit to a plan to get to net zero emissions by 2050, in line with the Paris Accord."

Echoing several of Mr Johnson's general election campaign slogans, Heathrow said a third runway was "essential to achieving the PM's vision of Global Britain', adding: "Let's get Heathrow done."

Image: Heathrow Airport has witnessed several protests by environmental campaigners

Heathrow ruling allows PM to change tack

by Paul Kelso, business correspondent

The repercussions of this judgment will be felt well beyond the suburbs and villages surrounding Heathrow.

The Appeal Court justices have not just lifted the immediate threat of demolition from homes in the path of the third runway.

By finding against the government on environmental grounds they have raised the bar for all infrastructure projects, public and private, and prioritised consideration of the impact of carbon emissions.

Image: Campaigners celebrate outside court

Environmental groups argued that the government's decision to approve the third runway was unlawful because it failed to take account of the Paris climate accord, under which the UK pledged to work to keep global temperature increases below 2C.

The original judgment was emphatic however that the Paris commitments had not been incorporated into UK law and therefore had no effect.

Overturning that position is a stunning triumph for environmental groups and a landmark moment for campaigners, regulators and developers.

Until now pledges to cut carbon emissions, including the government's target of hitting net-zero by 2050, have been theoretical, more easily said than done. This judgement turns the rhetoric into concrete, practical case law.

Image: Climate campaigners were delighted with the news

The judgment does not rule out further expansion of UK airports, but it does offer an opportunity for the government to change tack, perhaps returning to plans for Gatwick.

Boris Johnson was always publicly opposed to Heathrow's expansion, but any sense of triumph in the PM's circle may prove pyrrhic. Any expansion of airports, wherever they are, will now be much harder to get off the ground.