OPPONENTS of a third runway at Heathrow Airport are preparing to take the government to court after MPs voted overwhelmingly  to support its construction.

MPs voted 415 to 119 for the proposals last night — a majority of 296.

Four nearby London councils — Wandsworth, Richmond, Hillingdon and Hammersmith & Fulham — along with Greenpeace and London Mayor Sadiq Khan are to ask the High Court for permission for a judicial review of the expansion.

Greenpeace UK executive director John Sauven said: “If ministers don’t want to uphold the laws protecting us from toxic fumes and climate change, we’re going to ask a court to do that.”

Simon Dudley, leader of the Tory-run Windsor & Maidenhead Council whose area overlaps with PM Theresa May’s constituency, suggested that it might too join the court challenge.

Boris Johnson, who had promised to go as far as laying his life on the line to oppose the expansion, conveniently missed the vote by flying to Afghanistan, only returning today.

The Foreign Secretary was mocked for failing to appear, with MPs shouting: “Where’s Boris?” Had he rebelled he would likely have had to resign from his Cabinet job.

Labour officially opposes the move but allowed MPs a free vote. A total of 119 Labour MPs voted for it and 94 — including leader Jeremy Corbyn — voted against.

Unions Unite and GMB are backing the building of a third runway, believing that it would bring an extra 114,000 jobs around the airport.

Environmental experts warn that there is no way to square Britain’s  climate change targets with the extra emissions from flights.

Shadow chancellor John McDonnell warned that it was “a defining vote” on climate change.

“If we are to tackle climate change we have to restrict the growth of aviation to 55 per cent. However, as has been evidenced in the debate, it looks as if it might hit 90 or 100 per cent by 2050.

“That means that regional airports … or other sectors of industry will be constrained within our economy. To be frank, on past evidence we will not meet those targets, so we will jeopardise our potential to tackle climate change.”

Green MP Caroline Lucas noted that “aviation already has a uniquely generous allocation for climate emissions” and called for regulation such as a frequent flyer tax to reduce demand.