The three main candidates for next year's London Mayoral elections, including London Mayor Sadiq Khan, have all spoken out against the expansion of Heathrow Airport, after the Supreme Court ruled in favour of the airport this morning. 

The UK's highest court overturned February's decision by the Court of Appeal, which ruled that plans for a third runway at Heathrow were unlawful. 

The case centred around the UK's commitments to the 2015 Paris Agreement, which environmental campaigners argued were not taken into account when the Government greenlit plans for the runway. 

However, the Supreme Court unanimously decided that the then Secretary of State Chris Grayling had taken the commitments into account, and quashed the Court of Appeal's ruling. 

The mayoral candidates for Labour, the Conservatives and the Liberal Democrats all took to social media to voice their displeasure at the decision.

Khan tweeted: “This decision to allow Heathrow Airport a third runway will have a damaging impact on air quality, noise and London's ability to achieve net-zero carbon by 2030. I urge Heathrow to drop these damaging plans and work with us on a cleaner, greener recovery.”

Conservative candidate Shaun Bailey added: “I’m disappointed that the Supreme Court ruled in favour of expanding Heathrow. London should be the greenest city in the UK — but this decision takes us many steps backwards.

“I've campaigned against a third runway for years. And I continue to stand with the campaigners who have led the fight against Heathrow’s third runway. And I want to make it clear that the fight’s not over.

“As Mayor, I’ll continue to oppose a third runway. And I’ll work with campaign groups and residents to improve the quality of life for people under Heathrow’s flightpath.”

And in a statement, Liberal Democrat candidate Luisa Porritt said: “This decision does not change reality: a third runway at Heathrow airport will break our international obligation to tackle the climate emergency, as outlined in The Paris Agreement.

"Boris Johnson said he accepted the previous ruling, now he must hold his nerve and rule out the expansion of Heathrow Airport anyway.”

The decision to take the Court of Appeal's ruling to the Supreme Court was made by Heathrow itself, as the Government accepted the Court of Appeal's ruling. 

As such, even though the decision has been overturned, expansion plans will have to start again in Parliament and it’s unlikely the Government have the political will to restart the process.

Moreover, the coronavirus has taken its toll on the airport, with traffic down over 80% in October, as Paris’ Charles De Gaulle overtook it as the busiest airport in Europe.

Not everyone is opposed to the decision however, as London's Chamber of Commerce welcomed the decision, and criticised the Government for accepting February's ruling. 

Richard Burge, chief executive of London Chamber of Commerce and Industry, said:

“The delivery of the Government's ambitions for Global Britain are dependent on world-class connectivity. That will require a UK hub airport, linked to the existing transport network.

"It’s hard to see where else is better positioned to deliver that than Heathrow.  Frankly the Government should have been making the case, as this was never just about commercial enterprise, but about the future of the country’s national infrastructure.

“Heathrow, and indeed other London airports, have already made substantial commitments to sustainability and net zero, and are supporting airlines in their emissions reduction through green innovation. 

“This verdict now presents a chance for the UK to have future-proofed connectivity, for London to maintain its world city economic role for the benefit of the whole of the UK, and for Britain to show that will be a global leader in sustainable aviation."

The future of the runway remains unclear, as Prime Minister and Hillingdon MP Boris Johnson once claimed he would lie down in front of bulldozers in order to prevent the third runway being built.