With air capacity at a premium in the South East, the race to expand London’s major airports is on.

Plans to enlarge Heathrow, Gatwick, Stansted and Luton are either underway or have been submitted.

Some, like the potential third runway at Heathrow, have yet to clear major hurdles, including a crunch parliamentary vote on expanding Britain’s largest facility next month.

The UK’s last major runway was Manchester’s second, constructed all the way back in 2002.

While expansion plans are supported by industry leaders and stakeholders, airports naturally face opposition from their surrounding communities and residents.

If borne out to the full extent of current proposals, London’s big four will increase their capacity by more than 150 million passengers per annum by the 2040s.

But which of the projects will be delivered first?

One of Britain’s most contested national infrastructure debates has been the potential enlargement of Heathrow and construction of a third runway to the northwest of the airport.

The country’s aviation behemoth currently handles more than 84 million passengers a year and operates at nearly 99 per cent capacity.

But its location within the M25 and near relatively built-up areas has seen any expansion face fierce backlash, with campaigners saying any further development is inconsistent with the UK’s climate objectives.

Despite alternative proposals for a new facility elsewhere, including a mega-airport in the Thames estuary proposed by Boris Johnson, the Airports Commission concluded in 2015 a Heathrow expansion was the most cost-effective solution to capacity issues in the South East.

Proponents of expanding Heathrow point to its strategic location outside the capital and its complementary role to regional hubs.

Thomas Woldbye, the CEO of Heathrow Airport Limited, wrote last week in the FT that investors would be deterred from the UK if the third runway project was not allowed to proceed.

‘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’, he told the Commons transport committee on Wednesday.

A critical juncture in the Heathrow saga awaits next month, when the Heathrow Expansion National Policy Statement is due to conclude its parliamentary review.

One major roadblock persists – Britain’s revolving door of leaders and cabinet ministers precluding a consistent government line on the matter.

Since becoming prime minister in July, Andy Burnham has declined to back a third runway, indicating his preference for investment in regional hubs, including in his own city of Manchester.

The Labour leader said he wanted to wait for the outcome of a fresh public consultation launched in July.

However, the Chancellor, John Healey, was more outgoing with his support for the £33bn project, adding this week that Heathrow has ‘always been a case for growth’.

A final development decision is not expected to be made until 2029, meaning the new runway would not be operational until 2039 at the earliest, having been originally slated for 2035.

It’s far from the UK’s most glamorous airport, but the Essex hub is the first of the block to boost its numbers, albeit with the least ambitious scheme.

Work is already underway to expand and improve Ryanair’s largest base in a £1.1billion programme that will raise passenger numbers to 51 million by 2040.

The scheme will extend Norman Foster’s original 1980s single-terminal building northwards, decommissioning the passenger transit train that currently shuttles travellers to the satellite piers.

From next year, passengers will be bussed to the remote pier as new ‘skylink’ bridges are constructed.

There’s also more light promised for the currently crowded and chaotic departure lounge, with plans for a new airy space with views of the apron.

Proposals to expand Luton Airport received a boost this summer after the Supreme Court rejected an application to appeal permission to increase passenger numbers to 32 million per year by 2043.

The project, which includes a second terminal, was originally unveiled in February 2022, when a more modest plan to raise capacity to 19 million passengers per annum was still clearing the courts.

Unlike its rivals, which are all owned and managed by investment companies, Luton Airport has the distinction of being operated by Luton Rising, a firm controlled by the local authority.

A report by the Examining Authority, the independent body that assesses major infrastructure projects, had concluded that the expansion would harm surrounding areas, including the Chilterns national landscape, and add to road traffic.

The findings, however, were rejected by Transport Secretary Heidi Alexander, who ruled the environmental impacts of the scheme were outweighed by its economic benefits.

The final roadblock was removed this summer, after a judicial review brought by the environmental campaign group LADACAN was rejected by the Supreme Court.

Britain’s second largest hub has faced one major hurdle in its quest to add capacity – securing permission for a second runway.

The world’s busiest single-runway airport is already making improvements to its terminal buildings, including a £140million extension to the North Terminal’s satellite pier.

For 40 years, Gatwick was prevented from developing a second runway by a longstanding agreement with West Sussex Council.

However, that constraint was lifted after the deal lapsed in 2019.

A £2.2billion project to bring the facility’s northern runway – currently used as a backup strip – into full operation was granted governmental consent in September 2025.

Bosses say the privately funded project will boost reliability and reduce delays and cancellations.

A series of legal challenges came to a head in August this year, when the Court of Appeal dismissed the remaining lawsuit, with dual-runway operations expected to commence by 2030.

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