A THIRD runway at London’s Heathrow Airport was given the go-ahead today despite strong opposition to the expansion plans.

The project, debated for years, was finally approved at a meeting of ministers on the Cabinet’s economic subcommittee, a decision “based on national interest and detailed evidence,” Transport Secretary Chris Grayling announced in the Commons. MPs will be given a vote on the scheme by early July.

Shadow chancellor John McDonnell, whose Hayes & Harlington constituency is home to the airport, wrote on Twitter: “I remain implacably opposed to expansion at Heathrow.”

He added that after listening to Mr Grayling, he was “even more convinced that this would be a costly environmental and social disaster that will never be built.”

Shadow transport secretary Andy McDonald said Labour would hold the proposed expansion up to four tests.

“Expansion should only happen if it can effectively deliver on the capacity demands, if noise and air-quality issues are fully addressed, if the UK’s climate-change obligations are met in their entirety and that growth across the country is supported,” he said.

“We owe it to future generations to get all of these factors absolutely right — but if the correct balance isn’t found then the law courts will quite rightly intervene.”

Many environmental and residents’ groups are opposed to the runway over concerns about high levels of emissions and noise.

Greenpeace UK executive director John Sauven said: “Green-lighting a new runway at Heathrow on World Environment Day is like handing out free cigarettes on World Health Day.

“This airstrip alone will load the atmosphere with as much extra carbon as some entire countries pump out. It would make Londoners’ air more dangerous to breathe, contributing to an air pollution crisis that’s already cutting short thousands of lives.

“It’s time the government took seriously its commitment to protect the environment by building a low-carbon economy. Trains, not planes, for short-haul journeys and a tax on frequent flyers is needed to prevent aviation emissions from rising.”

John Stewart of anti-Heathrow expansion group Hacan said it was “a bad day” for residents who “will face a tsunami of noise.”

“Many people who will be under new flights paths will find their lives changed forever,” he said.

“We will continue to oppose a new runway but, obviously, if it becomes inevitable, we will fight for the best conditions possible for residents.”