Prime Minister Andy Burnham has signalled he would prefer expansion at Manchester Airport over a third runway at Heathrow, despite previously calling the west London project "a good idea".

Speaking to Nick Ferrari on LBC after his maiden conference speech as Labour leader, Burnham said he would wait for the outcome of the government's consultation on Heathrow expansion before deciding. But he pointedly raised "concerns" about the scheme while noting that Manchester already has spare capacity.

"There's been a consultation, and it's really important given it's such a decision of importance for the whole country, to take time to see the outcome of the consultation," Burnham said. "Obviously, Heathrow Airport is a huge economic driver for the country, but there are concerns, and those concerns need to be considered alongside that."

The intervention comes days after Burnham refused to back the third runway outright, drawing criticism for omitting airport expansion entirely from his conference speech in Liverpool.

The numbers at stake

The third runway scheme carries an estimated £33 billion price tag, including £1.5 billion to realign the M25, and is expected to be fully privately financed. Backers claim it could add up to £40 billion a year to the UK economy and create around 100,000 jobs.

The project would lift Heathrow's capacity to 756,000 flights and 150 million passengers annually. The airport currently aims to secure planning permission by 2029 and have a third runway operating by 2039 — a timeline already four years later than the original 2035 target, and one that airport bosses themselves have said the government's initial schedule cannot deliver.

Manchester first?

Pressed on his personal position, Burnham noted: "I'm on the record as saying that Heathrow could be a good idea." But he immediately pivoted to his old constituency. "As Mayor of Greater Manchester, I looked at the second runway at Manchester and it has capacity. So I think we do need to have a wider discussion about what is the right airport configuration for the country."

He went further, questioning whether brownfield-style logic should apply to aviation capacity: "In the long run, and where airports have got capacity, should that be used first before we allow further airport expansion? But I am having to say that I am listening to both sides of the argument. There is a strong case for it, but we do need to hear the arguments."

For an airline industry that has watched successive governments endorse and then waver on Heathrow expansion for over a decade, the remarks will read as a significant cooling. Labour's formal backing for the third runway was set out by former chancellor Rachel Reeves in January 2025, when the party framed the project as central to its growth agenda.

Khan factor

When Ferrari challenged Burnham on why the project was not proceeding faster, the Prime Minister pointed to opposition within the capital. "Ask some of the Members of Parliament in London, the Mayor of London. There are other voices who don't agree."

Mayor of London Sir Sadiq Khan has long opposed the expansion, citing the effects of increased flights on the capital's air quality. When Ferrari quipped that the Mayor seemed to have more sway than the Prime Minister, Burnham replied: "Well, no, but it's a very important voice."

Transport Secretary Heidi Alexander recently made the government's strongest case for the scheme, arguing an expanded Heathrow could serve as "the country's front door" for tourists from China and India, and that climate concerns around increased flights could be "holistically" offset elsewhere in the economy.

That argument now sits alongside a Prime Minister openly musing whether Britain's aviation growth should instead be routed through airports that can absorb it without new runways. With the consultation outcome pending and Burnham refusing to commit, the 2039 in-service date that Heathrow itself calls ambitious now depends on a decision the new Prime Minister shows little urgency in making.