Jeremy Corbyn has suggested it would not be easy to whip Labour MPs to vote against a third runway at Heathrow, despite his personal opposition to the infrastructure project.

The Labour leader said he has not yet decided whether to hold a free vote, but it could be difficult to get his MPs to fall into line with his view that the proposed project would cause harmful pollution and noise.

A vote on Heathrow is more likely to go through if Labour MPs are allowed to vote with their conscience, as there are dozens of Conservatives who are opposed to expansion at the airport in west London.

Theresa May is expected to announce a decision within weeks about whether to proceed with expanding airport capacity at Heathrow, which was recommended by the Davies commission.

It was reported in the FT on Thursday that government whips believe they have the numbers to push it through the House of Commons if there is a decision in favour.

However, the numbers are particularly uncertain because the prime minister is likely to give her own MPs a free vote to stop the resignations of a number of cabinet ministers who have constituencies that would be affected.

Artist’s impression showing how Heathrow could look with a third runway. Photograph: Heathrow Airport/PA

It is thought a majority of Labour MPs would support the scheme if given freedom to vote how they like, even though Corbyn and John McDonnell, the shadow chancellor, are against the plan. The Scottish National party has hinted it could be in favour if given assurances about routes to Scotland.

Speaking to the Guardian, Corbyn said he had never been a supporter “because of the issues of noise and pollution across west London”. He acknowledged there was a “huge debate in the party about it” and his shadow cabinet would have to “have a discussion and debate and try and work out a way forward but also improve rail links so we reduce the number of internal flights”.

Asked whether he would ask his MPs to vote against the plan, Corbyn said: “What I’ve discovered is whipping Labour when Labour doesn’t want to be whipped is not an easy thing to do.”

Corbyn has already held free votes on Trident and Syria as Labour was so split on the issues, with many MPs taking a different view to their leader.

It is still not certain that May, whose Maidenhead constituency is near the airport, will opt for Heathrow expansion over Gatwick or another option.

There is huge pressure on the prime minister to make a decision after years of procrastination by David Cameron, who was reluctant to break a pre-2010 promise he made about opposing Heathrow expansion with “no ifs, no buts”.

A shadow cabinet reshuffle, including replacing Andy Burnham so the shadow home secretary can concentrate on the Greater Manchester mayoral race, is expected within weeks.

Allies of Corbyn have insisted he is able to fill a shadow cabinet without elections from the PLP, but critics including the deputy leader, Tom Watson, have called for a return to elections by MPs.



The Unite union’s general secretary, Len McCluskey, said he believed there would be at least partial elections, as long as the leader had the power to sack MPs from their positions. “I can envisage in a fairly short space of time, a matter of a few weeks, that he will have put together a shadow cabinet to deal with the election element of the PLP,” he told the Telegraph.

McCluskey said there would be no need to change the party rulebook or have it approved by the NEC, but elections could be at the discretion of the leader. “Jeremy can offer X number of seats – it doesn’t need to be a rule – it is in his gift. And I think he may well do that.”

McCluskey also repeated his challenge to Watson, his former flatmate, to “test his mandate” as the party’s elected deputy leader. “I fear for him what the result would be,” he said.