Heathrow airport's third runway is to be delayed by four years, meaning it will not be operational until 2039, with Rachel Reeves' £49 billion plan deemed "unrealistic". Airport bosses at the UK's busiest airport have told ministers that the current 2035 deadline, set by the former Chancellor, is not achievable.
Reeves' 2035 target under fire
Ms Reeves threw her support behind the third runway plans last year, insisting it would be completed by 2035 even though it was considered an ambitious goal at the time. She used a major infrastructure speech to announce the Government would support the project as a means of growing the economy, and also said it would create 100,000 jobs.
Heathrow, which handled a record-breaking 84.5 million passengers in 2025, sees this deadline as increasingly difficult to deliver without additional steps to simplify the planning process.
Airport bosses push for faster delivery
Its bosses believe it could be delivered more quickly, but that this may require further regulatory red tape to be removed beyond reforms the Government has already made to planning law.
A Heathrow spokesperson said: "It's right that ambitious targets were set; the sooner expansion begins, the sooner the whole UK will benefit. Our focus has always been to secure planning permission by 2029.
"Once achieved, the runway will be open within a decade – and the benefits of expansion can be felt from today. At least 108,000 new jobs and billions invested in supply chains in every part of the country.
"This is a national project, 100% privately financed, which will support growth today and secure the UK's position in the global economy once the runway opens."
Government response and project details
Meanwhile, the Department for Transport (DfT) said the project's timeline had "always been ambitious" and that it would continue to work with stakeholders "at pace" on the matter.
A DfT spokesperson said: "There is currently no live planning application for a third runway, and we cannot comment on ongoing consultation processes or prejudice them in a way that will only delay progress.
"The timeline has always been ambitious.
"We'll continue to work with promoters, including Heathrow, and all other stakeholders at pace to ensure the right framework is in place for which a planning application for a third runway could be considered."
The proposed expansion would involve demolishing hundreds of homes, diverting rivers and rerouting the M25 between junctions 14 and 15 through a tunnel beneath the new runway. The expansion could increase the airport's annual flight limit from 480,000 to 720,000 and see it average nearly 2,000 flights a day.
London Mayor Sadiq Khan has formally opposed the plans, citing concerns over increased noise, air pollution and its potential impact on climate change. Sir Sadiq has argued that he has seen no evidence the proposals were compatible with a credible path to net zero.
"The evidence suggests Heathrow expansion is a risk that we simply cannot afford to take."
