London's major airports are competing to expand first, with combined plans that could add more than 150 million passengers per year by the 2040s. Expansion projects at Heathrow, Gatwick, Stansted and Luton are either underway or have been submitted, though some face significant obstacles.
Heathrow's third runway faces parliamentary vote
Heathrow, which handles more than 84 million passengers annually at nearly 99 per cent capacity, is the subject of one of Britain's most contested infrastructure debates. The proposed third runway to the northwest of the airport has faced fierce backlash from campaigners who argue further development is inconsistent with the UK's climate objectives.
The Airports Commission concluded in 2015 that Heathrow expansion was the most cost-effective solution to capacity issues in the South East, despite alternative proposals such as a mega-airport in the Thames estuary suggested by Boris Johnson. Proponents point to the airport's strategic location and its complementary role to regional hubs.
Political divisions over Heathrow expansion
Thomas Woldbye, CEO of Heathrow Airport Limited, wrote in the Financial Times that investors would be deterred from the UK if the third runway project was not allowed to proceed. He told the Commons transport committee: 'There is nothing of the size of Heathrow, and there is nothing of the size of Heathrow that has the UK-wide positive consequences. Sixty per cent of the economic benefit of a runway at Heathrow will be felt throughout the entire country. If you compare that with other projects, I do not think that is the case.'
A critical parliamentary review of the Heathrow Expansion National Policy Statement is due to conclude next month. Prime Minister Andy Burnham has declined to back a third runway, preferring investment in regional hubs, while Chancellor John Healey has expressed support for the £33bn project, saying Heathrow has 'always been a case for growth'. A final development decision is not expected until 2029, meaning the new runway would not be operational until 2039 at the earliest, having originally been slated for 2035.
Stansted and Luton push ahead
Stansted is the first to boost its numbers with the least ambitious scheme. Work is underway on a £1.1bn programme that will raise passenger numbers to 51 million by 2040. The project extends Norman Foster's original 1980s single-terminal building northwards, decommissioning the passenger transit train, with passengers bussed to the remote pier as new 'skylink' bridges are constructed.
Luton Airport's expansion received a boost this summer when the Supreme Court rejected an appeal against permission to increase passenger numbers to 32 million per year by 2043. The project, including a second terminal, was unveiled in February 2022. Transport Secretary Heidi Alexander rejected an Examining Authority report that concluded the expansion would harm surrounding areas, ruling that economic benefits outweighed environmental impacts. A judicial review by environmental campaign group LADACAN was rejected by the Supreme Court.
Gatwick's second runway nears reality
Gatwick, the world's busiest single-runway airport, is making terminal improvements including a £140m extension to the North Terminal's satellite pier. A longstanding agreement with West Sussex Council prevented a second runway for 40 years, but the constraint lapsed in 2019. A £2.2bn project to bring the northern runway into full operation was granted governmental consent in September 2025. After a series of legal challenges, the Court of Appeal dismissed the remaining lawsuit in August, with dual-runway operations expected to commence by 2030.
