UK airports London: crowded skies, delayed runways

London is served by five main airports: Heathrow, Gatwick, Stansted, Luton and London City. In 2025 they handled about 178 million passengers between them, close to 60% of all UK air travel. Heathrow alone carried 84.5 million, and it is full. The UK airports London depends on are short of runway capacity, and a decade of argument about how to fix that has not produced a single new runway. Most coverage explains how airports work. It rarely counts who pays for expansion, or how long the customer will wait.

The reality is that capacity is a form of wealth. A country that cannot add it quickly, or cheaply, pays in higher fares, lost routes and investment that goes elsewhere.

UK airports London at a glance

• Heathrow handled 84.5 million passengers in 2025, up 0.7% on 2024, which makes it by far the busiest airport in the United Kingdom.
• Gatwick handled 42.8 million, down 1.1%, Stansted 29.8 million, up 0.2%, and Luton 17.8 million, up 4.9%.
• London City handled 3.7 million, up 4.6%, and the five airports together carried roughly 178.5 million passengers.
• UK airports as a whole handled about 300 million passengers in 2025, a record, so the London five account for close to three journeys in every five.

Source: Civil Aviation Authority, UK airport data, calendar year 2025 (terminal passengers); percentage changes calculated by the Society.

UK airports list: which airports serve London and the rest of Britain?

Beyond the capital, the largest UK airports include Manchester, Edinburgh, Birmingham, Glasgow and Bristol. But London’s five remain the gateway for long-haul travel, freight and business. Heathrow is the national hub, linking cities across the Union, including Edinburgh, Glasgow and Aberdeen, to the world. Gatwick, Stansted and Luton are the main bases for low-cost and leisure carriers, and London City serves the financial district with short business routes.

The hub matters because it is a shared national asset. A business in Aberdeen or Cardiff that can reach Singapore or New York in one connection is a business that can sell there. That is one reason the cost of expanding Heathrow is a question for the whole Union, not merely for west London.

Why are London’s airports full? The monopoly that was broken, and the runway that was not built

Until 2009, one company owned Heathrow, Gatwick and Stansted. Regulators concluded that a single owner of the capital’s three largest airports had little reason to compete or to invest for passengers, and ordered the sale of Gatwick and later Stansted. The result is instructive. Gatwick, under separate ownership, now has a fully privately financed plan for a second runway. Competition between airports did what regulation alone could not.

Heathrow, by contrast, remains a regulated monopoly of a kind: it operates close to the limit of its two runways, its charges are set by the Civil Aviation Authority, and its expansion has been argued over since an independent commission recommended it in 2015. Why has a project endorsed by a national commission taken more than a decade without a single metre of tarmac? Why must passengers be asked to pay in advance for a runway that may not open for another thirteen years? And why does the state, rather than the market, decide where the capacity should go? The answers lie in planning, politics and cost.

Heathrow’s third runway: a bill of £49 billion, and who pays

The case for the third runway is serious. More capacity means more routes, more competition on fares, more freight and more trade. In November 2025 the government selected Heathrow’s scheme as the basis for its policy review, in preference to a rival proposal. The scheme is costed at around £49 billion overall, of which the runway itself accounts for some £21 billion, and Heathrow aims to secure planning consent by 2029. Reports in 2026 suggest that opening is now more likely towards 2039 than the 2035 originally hoped.

The difficulty lies in the bill and the timetable. In July 2026 the regulator decided that Heathrow may recover up to £320 million of early planning costs through higher charges from 2028. On the regulator’s own estimate that adds about 15 pence per passenger, rising to roughly 30 pence later. For a family of four, that is somewhere between 60 pence and £1.20 more each time they pass through the airport, before any other increase. It is a small sum, and it is a payment for a runway that does not exist.

Best case, the runway is built close to budget and within a decade, and the early charge is repaid in cheaper fares and new routes. Worst case, costs overrun, consent slips again and passengers fund a project for a generation before they see a benefit. A project of £49 billion that depends on regulatory goodwill at every stage is not a plan. It is a hope with a spreadsheet.

Gatwick’s second runway: £2.2 billion, privately financed

Compare the neighbour. On 21 September 2025 the Transport Secretary granted development consent for Gatwick to bring its northern runway, now used only for taxiing, into full operation alongside the main runway. The scheme costs about £2.2 billion, all privately financed, and the airport expects it to support around 100,000 additional flights a year and some 14,000 jobs. Those are the operator’s estimates, and they should be treated with the usual caution.

The comparison speaks for itself. Heathrow’s overall scheme costs about twenty times as much as Gatwick’s and will arrive, on current estimates, many years later. The regulator has said that Gatwick’s case for expansion stands even if Heathrow also expands, which is exactly what a competitive market for airports should look like. Capacity added by private money, at private risk, is capacity the taxpayer does not guarantee.

The climate objection, and a sense of proportion

Opponents argue that more runways mean more emissions, and aviation is certainly a visible source of them. The Society’s analysis suggests that the cost of mitigation through mandates and fuel premiums is likely to exceed the cost of adaptation, and that those costs fall on ordinary passengers as higher fares. A policy that prices the family holiday out of reach while the long-haul business class continues untouched is a regressive tax by another name. Technology, including more efficient aircraft, will do more to cut emissions per passenger than a ban on capacity ever could.

What should be done about UK airports London needs?

• Fund expansion with private capital at private risk, and refuse any taxpayer guarantee for cost overruns.
• Keep the capital’s airports in separate ownership, so that competition rather than regulation disciplines price and service.
• Limit what passengers can be charged before a runway opens, and require the regulator to publish the full cost per household.
• Set a fixed planning timetable for major airport schemes, so that a consent decision takes years rather than decades.
• Protect regional links to the hub, so that the benefits of expansion reach every nation of the Union.

Frequently asked questions

What are the main UK airports serving London? The five main airports are Heathrow, Gatwick, Stansted, Luton and London City. Together they handled roughly 178.5 million passengers in 2025. Heathrow is the largest at 84.5 million, followed by Gatwick at 42.8 million, Stansted at 29.8 million, Luton at 17.8 million and London City at 3.7 million.

What is the busiest airport in the UK? Heathrow, which handled 84.5 million passengers in 2025, roughly twice as many as Gatwick, the next largest. It operates close to the limit of its two runways, which is why proposals for a third have been debated for so long and why its charges are regulated by the Civil Aviation Authority.

Will Heathrow get a third runway? It has not yet received planning consent. In November 2025 the government selected Heathrow’s scheme as the basis for its policy review. Heathrow targets consent by 2029, and reports suggest opening around 2039. The scheme is costed at about £49 billion overall, with the runway itself about £21 billion.

Is Gatwick getting a second runway? Yes. Development consent was granted on 21 September 2025 to bring Gatwick’s northern runway into full use alongside the main runway. The roughly £2.2 billion scheme is privately financed, and the airport expects it to support around 100,000 more flights a year.

Conclusion: the UK airports London needs are built by competition, not committee

The UK airports London relies on are among the busiest in the world, and they are full. The fastest, cheapest route to more capacity has been to break up a monopoly, let separate owners compete and allow private capital to take the risk. The slowest, dearest route has been a state-sanctioned scheme of £49 billion that asks passengers to pay now for a benefit due in the next decade and a half.

It is, of course, for Parliament to decide. But it should decide knowing the price. A runway is a bridge to the world, and a nation that takes thirty years to build one should not be surprised when traffic goes elsewhere.