How much will a Heathrow expansion legal battle cost?

The Mayor has been urged to reaffirm his opposition to the proposed Heathrow expansion, and to make clear in his 2025-26 budget what funds are available for legal action against the Government, if the expansion is pursued.

The London Assembly has today also called on the Mayor to meet with West and South West London residents who would be affected by the proposed Heathrow expansion.

Gareth Roberts AM, who proposed the motion, said:

“I am delighted the Assembly has recognised the horrific environmental impact that a third runway at Heathrow will have on our city.

“The Mayor has made his position known, but we now compel him to write to the Chancellor, meet local South West London residents to hear their concerns and – crucially - ring fence funds in his forthcoming budget for a legal challenge against expansion plans.

“A third runway at Heathrow Airport must be opposed at all costs to protect the health and wellbeing of Londoners.”

Zack Polanski AM, who seconded the motion, said:

“Heathrow expansion is an insult to Londoners who just don’t want it built: they don’t want more noise, more pollution or more noisy flights overhead.“The Mayor says he's against a third runway but it's time for him to put his money where his mouth is and fund legal action against this direct attack on our climate goals.

“We simply won’t meet our targets if we say ‘fly baby fly’ to developers and businesses when so many green alternatives exist.”

The full text of the motion is:

This Assembly notes:

• The Chancellor of the Exchequer has confirmed the Government supports the future expansion of Heathrow Airport, including the building of a third runway.
• That as recently as the January 2025 Mayor’s Question Time, the Mayor of London has stated his opposition to this expansion, in the past commenting that he would support legal action against the Government.
• That a third runway at Heathrow would have significant consequences many areas of London, particularly in the West and South West of the city. The environmental damage, increased noise pollution, and disruption to local communities are too high a price to pay, when viable alternatives exist that can support sustainable economic growth without compromising Londoners’ health and future.

This Assembly calls on the Mayor to:

• Reaffirm his position opposing any expansion of Heathrow or construction of a third runway, in writing to the Chancellor.
• Agree to meet with local resident groups across London who would be affected by Heathrow expansion to hear their concerns first hand and assure them of his plans.
• Make clear in his Final Draft Budget 2025/26 - due for publication on 17 February - that funding is available for legal action against the Government if expansion plans are pursued.

The meeting can be viewed via webcast or YouTube.

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