Len McCluskey has written to all Labour MPs urging them to back Heathrow expansion on Monday, a move that puts the head of the Unite union directly at odds with Jeremy Corbyn.

He said they had “the opportunity to create hundreds of thousands of new jobs” by backing the government’s decision to build a third runway.

“We urge you to make the right choice,” McCluskey wrote in the letter seen by the Guardian. “Your action in the next few days matter to us.”

Jeremy Corbyn has said his party’s policy will be to oppose expansion because the plans do not meet Labour’s four tests on issues such as air pollution and jobs. However, Labour MPs will have a free vote on the issue unlike their Tory counterparts, who will be on a three-line whip to support the plans.

Unite, one of the Labour leaders’s most powerful backers, has long been supportive of a third runway at Heathrow. The union represents more than 34,000 workers at the airport in west London and has been a powerful lobbying force behind the move to expand.

In the letter, which is co-signed by the Back Heathrow campaigner Parmjit Dhanda, McCluskey said the expansion would allow the union to collectively bargain for thousands more members, saying it would create hundreds of thousands of new unionised jobs at Heathrow, regional airports and on transport networks.

“In the coming days you will have the chance to make a historic and positive difference to the lives of Unite members, their sons and daughters, and generations to come,” he wrote.

“You can ensure our country remains a world leader in aviation and aerospace, industries containing high-quality, unionised jobs.”

A Labour source said the party accepted there would be differences of opinion. “On the third runway, Labour has been clear and consistent. It doesn’t meet the four tests we set it, the proposals don’t even meet one of them,” the source said.

“But we also recognise this is a longstanding issue which MPs have strong views on. That’s why we think it’s right that a free vote is given and that all parties should offer a free vote. Perhaps the foreign secretary [Boris Johnson] might be able to pop back for the vote if that’s the case?”

McCluskey’s action will put him at odds not only with Labour’s official policy, which is now to oppose expansion, but with key allies in the party, including the shadow chancellor, John McDonnell, a fierce opponent of Heathrow expansion.

Heathrow is based in McDonnell’s Hayes and Harlington constituency. He said he would vote against not only because homes would be demolished and air pollution would rise, but also because to show he was serious about tackling “the devastating impact of climate change”.

Jon Lansman, the founder of grassroots pro-Corbyn group Momentum, said Labour should be whipping MPs against the plans. “There won’t be any jobs if we don’t stop climate change making the planet uninhabitable for human beings,” he tweeted.

More than 100 Labour MPs have indicated to government whips they are planning to vote in favour of expansion, meaning the plans should comfortably pass the Commons regardless of any Tory rebellion.



It remains to be seen whether any shadow cabinet ministers will vote for expansion. The shadow education secretary, Angela Rayner, has signed a letter from 21 Greater Manchester MPs, coordinated by Lucy Powell, offering conditional support for expansion as long as it is accompanied by the right regional transport strategy.

Conservative MPs may rebel in limited numbers, with one government source suggesting the numbers may be as low as five.But the rebellion will still be politically damaging given the high-profile of possible rebels.

Greg Hands, whose Chelsea and Fulham constituency lies under the Heathrow flightpath, resigned as international trade minister in order to oppose the plans. Other Tory rebels may include Zac Goldsmith, the MP for Richmond Park, and the former cabinet minister Justine Greening.

Johnson, an outspoken critic of the plans, will be out of the country for the vote. His destination is not being released in advance for security reasons.

The transport secretary, Chris Grayling, said the Commons was facing “a momentous vote that has been 50 years in the making and represents the biggest transport decision in a generation”.

He said MPs should seize the opportunity to take decisive action on Monday. “I hope colleagues from across the House will now put aside party and political differences to take a decision in the long-term national interest.”

He also wrote a piece for the Telegraph in which he suggested the decision would be vital to Britain’s post-Brexit prospects. “We need to demonstrate clearly that our future lies very much at the heart of the world stage,” Grayling wrote. “There is no better way of doing that than by finally taking the decision to equip our hub airport with the capacity it needs.”

Greening, whose Putney constituency is also under the flight path, told the Guardian it was “deliberately misleading and deeply naive” for the government to say expansion would have no cost to the taxpayer, saying there would be funds needed for public subsidy of domestic routes and an estimated £10bn on new public trasnport costs.

“If Heathrow can’t get over air pollution limits, taxpayers have to pay for the runway they can’t use,” Greening said.

“It’s time DfT were frank with themselves, MPs and the public. However if they were honest about the huge problems and risks, they know this project would be dead in the water so instead they continue this charade. It’s a shockingly dishonest approach.”

Environmental groups warned in a joint statement that it would “morally reprehensible” to vote in favour of expanding Heathrow. The coalition, which includes Friends of the Earth, 350.org and Vote no Heathrow, said global temperatures were already 1.2C above the pre-industrial average.

They added: “The Arctic is likely to be ice-free in the summer as early as 2022, which will accelerate the warming. The melt and the disintegration of Antarctica is already running away uncontrollably driving up global sea levels.”

Six people from Vote no Heathrow have been on hunger strike for two weeks in protest against the government’s plans – with more than 50 fasting at some point. They have staged a series of direct action protests and say that these will be escalated in the coming months if, as expected, the vote goes through.

A spokesperson said: “Whatever happens in parliament we are here to stay – and the protests are only going to get bigger.”