Ed Miliband has said he will not resign if Labour backs a third runway at Heathrow despite his previous opposition.
The Energy Secretary, who was an outspoken critic of the plans when he was party leader, said the idea of him quitting was ‘ridiculous’.
However, London mayor Sir Sadiq Khan indicated that he will continue his opposition to the scheme, warning that a third runway is incompatible with protecting the planet.
Chancellor Rachel Reeves is expected to use a speech on growth next week to support the plan, as well as an expansion of Gatwick and Luton.
Her backing has raised questions about whether her fellow Cabinet members will fall into line or oppose the expansion of the west London airport.
Seven Cabinet members including Sir Keir Starmer, Mr Miliband, and Environment Secretary Steve Reed have previously voted against the scheme.
Mr Miliband was expected to be the most vocal government critic, but he insisted he would not quit over the government’s decision yesterday.
Asked if he would consider resigning if the plans go ahead, he said: ‘Don’t be ridiculous, no.
‘The whole of the Government is focused, and I’m focused, on delivering our clean energy mission as part of what we need to do as a country, as part of the Prime Minister’s mission and as part of meeting our economic growth mission – our number one priority.’
Mr Miliband’s refusal to say he would resign marks a departure from his previous views on a third runway.
He previously revealed that he nearly resigned from former prime minister Gordon Brown’s cabinet in protest at the plans.
When he became Labour leader in 2010, he ended Labour support for Heathrow’s expansion.
In 2018, he said he would vote against the plans saying ‘we owe it to future generations not just to have good environmental principles but to act on them’.
Mayor of London Sir Sadiq Khan, who won a third term in 2024 after saying he would oppose the expansion of London’s airports, said his views ‘haven’t changed’.
He told the London Assembly: ‘What Londoners know and the Government knows is the aviation sector is important for growth, jobs and prosperity, but we face a climate crisis and a climate emergency.’
He added: ‘The three big concerns that would need to be addressed if, in the hypothetical case, the speculation was to become a reality, is could a new runway be built that abides with carbon targets, concerns around noise pollution, and concerns around air pollution?
‘Should that speculation become a reality, we’ll of course consider the merits of that case.
‘But I’m quite clear, my views on the expansion of Heathrow by a new runway haven’t changed.’