The court ruled that proposals for the third runway as set out in the Government’s Airports National Policy Statement (ANPS) are unlawful due to their failure to take into account the UK’s commitment to the Paris Agreement on climate change.

“That, in our view, is legally fatal to the ANPS in its present form,” a summary of the court’s judgement said. “We have not decided, and could not decide, that there will be no third runway at Heathrow,” it clarified.

“The consequence of our decision is that the Government will now have the opportunity to reconsider the ANPS in accordance with the clear statutory requirements that Parliament has imposed.”

Responding to the judgement, Transport Secretary Grant Shapps, described airport expansion as a core part of boosting the UK’s global connectivity but said: “We have always been clear that Heathrow expansion is a private sector project which must meet strict criteria on air quality, noise and climate change.”

He added that the Government has no plans to appeal the court’s decision. “We take seriously our commitments on the environment, clean air and reducing carbon emissions. We will carefully consider this complex judgment and set out our next steps in due course.”

A Heathrow spokesman described the failure of the ANPS to sufficiently account for climate change as “eminently fixable” and said the airport intends to appeal to the Supreme Court. “In the meantime, we are ready to work with the Government to fix the issue that the court has raised.

“Expanding Heathrow,” the spokesman added, “is essential to achieving the Prime Minister’s vision of Global Britain. We will get it done the right way, without jeopardising the planet’s future”.

Legal challenges against Heathrow expansion were brought by a number of local authorities and the Mayor of London alongside climate campaigners Greenpeace, Friends of the Earth and Plan B.

The capital’s Mayor Sadiq Khan welcomed the “landmark” judgement as a victory for Londoners and future generations. “The Government must now finally see sense and abandon plans for a third runway at Heathrow,” he said.

Friends of the Earth climate campaigner Jenny Bates urged the Government to take the ruling as an opportunity “to play its full part in fixing the international climate crisis”.

“This means finally moving on from the climate wrecking Heathrow third runway project and ensuring the UK aviation sector actually cuts its climate emissions, rather than adding to them,” she said.

The Association for Consultancy & Engineering’s director of external affairs Julian Francis suggested that the ruling may have repercussions for future infrastructure decisions.

“The judgement’s implications are clearly wider than just Heathrow, as the judges have stated that climate change must be kept at the heart of all planning decisions and that developers and public authorities can be held to account if their proposed schemes negatively impact UK climate change commitments,” he said.

Meanwhile the Association of Directors of Environment, Economy, Planning & Transport has called for a new national aviation strategy to tackle both climate change and secure economic growth.

Chair of the Association’s transport and connectivity board Mark Kemp said: “A national strategy would set out a clear vision for a more sustainable aviation sector, benefitting the country, the environment, industry and local authorities.”

Also this week the broadcaster and naturalist Chris Packham began a legal challenge over the Government's decision to back High Speed 2, arguing the project will be incompatible with any net zero emissions target.

He also believes that the rail scheme will damage or destroy almost 700 wildlife sites including over 100 ancient woodlands. "Every important policy decision should now have the future of our environment at the forefront of its considerations," he said,"but in regard to the HS2 rail project I believe our Government has failed."

Law firm Leigh Day has sent a Pre-Action Protocol letter on behalf of Chris Packham, arguing that the decision to give go ahead to High Speed 2 was unlawful because it did not take into account the full environmental costs of the project.

A DfT spokesman said: “We are considering this and will respond in due course. We understand campaigners’ concerns and have tasked HS2 Ltd to deliver one of the UK’s most environmentally responsible infrastructure projects.

"When finished, HS2 will play a key part in our efforts to tackle climate change, reducing carbon emissions by providing an alternative to domestic flights and cutting congestion on our roads.”

(Photograph: Heathrow Airports Limited)