The EU referendum was one of the excuses used by David Cameron’s Government to delay a decision on a new runway in South-East England. Yet now the poll result has spurred a decision that, given the decades-long dithering, looks positively swift.

The Transport Secretary, Chris Grayling, confirmed the Government’s support for a new third runway to the north-west of the existing pair at Heathrow — the recommendation of the Davies Commission. Mr Grayling said: “We’ve thought long and hard about this. There were three very good options on the table.

“This is about taking the right decision for the United Kingdom, it’s about best doing what’s right for all the regions, with the best connectivity, saying Britain is open for business post-referendum.”

The long-awaited decision will trigger a host of legal challenges. Local authorities whose residents will be affected by additional noise and air pollution have already said they will seek to have the plan overturned. In addition, proponents of the alternative schemes — the “Heathrow Hub”, involving a longer northern runway, and a second runway at Gatwick, may challenge the basis for the decision.

Mr Grayling said: “Gatwick remains an important part of the British transport system.”

The London Mayor, Sadiq Khan, said the decision was “wrong for London, wrong for Britain.”

Zac Goldsmith, MP for Richmond Park and Mr Khan’s opponent in the recent mayoral election, has resigned his seat, triggering a by-election. He has been a long-standing opponent of expansion at Heathrow.