Prime minister said £49bn scheme was a ‘matter for Londoners’ as airport claims work could be delayed by four years
Andy Burnham has refused to back the expansion of Heathrow after the airport claimed the £49bn project could be delayed by up to four years.
The prime minister opposed construction of a third runway at the UK’s biggest airport while mayor of Greater Manchester, warning in 2018 that it risked further concentrating economic activity in the South-east at the expense of Northern England.

Yesterday, he told the BBC that the future of the airport was “a matter for Londoners”, adding: “I think we ought to hear the voice of people there first.”
A Heathrow spokesperson said: “We agree with the prime minister that local voices must be heard. We know from consistent polling over the last decade that communities support our plans for expansion, and support is only growing over time.”
Sadiq Khan, the mayor of London, has consistently opposed the expansion, warning last year of the “severe impact it will have on noise, air pollution and meeting our climate change targets”.
Former chancellor Rachel Reeves backed the project last year and pledged to open the third runway by 2035 after the government opted for the airport’s own Grimshaw-designed proposals over a smaller and cheaper scheme designed by Scott Brownrigg.
However, Heathrow claimed on Saturday that the expansion might not complete until 2039 without steps to simplify the planning process. The planning application alone is expected to cost up to £800m before it is submitted in 2027 or 2028, the airport said in May.
The Grimshaw scheme, which includes a full-length 3.5km runway, would require rerouting a section of the M25 through a tunnel, demolishing hundreds of homes and diverting nearby rivers.
It would be privately funded, with Burnham’s government confirming earlier this month that any expansion and surface infrastructure upgrades around the site “would be privately financed”.
The expansion is expected to increase the number of flights from the current cap of 480,000 a year to up to 720,000.
It would also significantly increase the amount of freight passing through the airport, which currently handles more than a quarter of the UK’s entire international goods trade by value.
The project has been backed by both the Unite and GMB Unions, with the latter saying on Saturday that “every year without a third runway is a year that new trade goes to France, Germany and the Netherlands instead of Britain”.
GMB London regional secretary Warren Kenny added: “Opponents of this runway will try to dress up a timetable as a verdict. It isn’t one. A project taking longer to build is not a reason not to build it. It’s a reason to start now.
“Heathrow has been clear that the hold-up is planning and red tape. Politicians can fix that. The chancellor [John Healey] is right to be clearing bottlenecks, and we want to see that go further and faster. Finalise the framework, hold the vote and get building.
“There are 108,000 jobs waiting on this decision. Every year of dithering is a year of apprenticeships not started, contracts not signed and wages not paid. Our members aren’t waiting for 2039. The jobs start the day the spades go in the ground.”
The £49b cost of the scheme covers both the third runway expansion and a modernisation of the airport’s current facilities, with the former split between £21bn for the runway and £12bn for associated terminal infrastructure.
















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