Last week’s Brexit vote could mean Heathrow expansion will not go ahead, especially if Boris Johnson succeeds David Cameron as Prime Minister, according to campaigners.

The EU referendum result and David Cameron’s subsequent announcement he would resign has cast doubt on whether the Government would announce its decision over a third runway at the airport on July 7-8 as previously indicated.

Stop Heathrow Expansion campaign coordinator, Robert Barnstone, said the referendum result revealed early last Friday morning suggested a new timetable for a runway announcement may appear.

He said: “If a leading Brexiteer and Heathrow expansion opponent, such as Boris Johnson, becomes the new Prime Minister this autumn, it could mean a very different situation on the question of runway capacity in London & the South-East."

“David Cameron, with his term as Prime Minister now entering its final phase, is unlikely to want to cause further damage within his own ranks on whether the highly controversial expansion of Heathrow goes ahead. A decision previously pencilled in for a fortnight’s time now looks substantially less likely."

John Stewart, chairman of campaign group Hacan, agreed and said the Brexit vote cast doubts over whether the third runway would ever be given the green light.

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He said: “The Prime Minister and the Chancellor have lost the fight of the lives. ‘Outers’ like Boris Johnson, who is fiercely opposed to Heathrow expansion, have won. At the very least, a decision on a new runway must now be up in the air.”

“A new Prime Minister would want to look again at its desirability, its deliverability and the cost its related rail and road infrastructure would impose on the public purse.”

“The Government had pencilled in July 7 or 8 to announce its runway decision.

"It may confirm its intentions over the next few days but it would surprising if a lame-duck Prime Minister risked further splits within the Conservative Party by making such a controversial decision just weeks before he leaves office.”

Ravi Govindia, leader of Wandsworth Council, said: “What our country needs now is strong leadership and unity, so attempting to push through the most divisive and unpopular infrastructure scheme in modern history is about the last thing any government should do.

"Everyone knows that London’s residents, councils, MPs and Mayor will all line up to fight this deeply damaging project and the front runners to be our next Prime Minister are also clearly opposed.

"It’s clear a fresh attempt at Heathrow expansion would fall flat on its face and we should focus on building a new runway at Gatwick so we have a realistic prospect of  delivering the aviation growth our economy needs.”

A spokesman from Heathrow said the case for expansion was stronger than ever before and only the west London airport can help Britain be a great trading nation.

He said: “It is the keystone that connects businesses of every size to markets across the world as the UK’s only global hub airport.

“Global connections are critical for a new outward-looking UK to help our businesses and economy to thrive - and with expansion we can deliver up to 40 new destinations on top of the 83 we serve now.

“We are confident that the Government will make the right choice for the future of the UK, putting the interests of the country first.

“We look forward to working with the Government and its agencies on next steps.”