British MPs voted overwhelmingly in favour of greenlighting the expansion of London Heathrow Airport, Europe’s largest, a decision that the government had described as the most important for transportation in the country for a generation. Prime Minister Theresa May had directed her Conservative MPs to support the project, while the opposition Labour Party allowed members to have a free vote. Lawmakers approved the expansion by 415-119, a majority of 296 votes in the 651-seat House of Commons. The decision on a third runway at Heathrow comes after years of study and debate over how and where to expand airport capacity in south-eastern England. Despite the Commons vote, approval of the £14 billion (Dh68.34bn) project is certain to be challenged in the courts. Mrs May’s government says it demonstrates Britain’s commitment to expanding international trade and transport links, and would have long-term economic benefits. Business groups have also strongly backed the government. They argued that increasing the capacity at Heathrow would be tantamount to putting out an "Open for business" sign, as Britain prepares to leave the European Union. “This is a really important moment in the history of this house and the history of this country,” Transport Secretary Chris Grayling told the House of Commons, as he appealed for lawmakers to “move on from decades of debate and set, to my mind, a clear path to our future as a global nation in the post-Brexit world”. Opponents object to the third runway on environmental, noise and financial grounds. Friends of the Earth described it as a “morally reprehensible” move that would result in Heathrow emitting as much carbon as the whole of Portugal. London's mayor, Sadiq Khan, has pledged to join local government councils in filing legal action to block the expansion and has said Heathrow already exposes the city to more aircraft noise than Paris, Frankfurt, Amsterdam, Munich and Madrid combined. He argues that the project would also push toxic emissions above legal limits. “This will be a critical moment, and for the sake of Londoners affected by poor air quality, disruption from noise and the costs needed to improve transport connections, I will do what I can to stop these poor plans,” Mr Khan said in a statement. The vote focused attention on the ongoing soap opera that is the Foreign Secretary Boris Johnson, whose constituency of Uxbridge and South Ruislip is close to the airport. Mr Johnson once pledged to lie down in front of bulldozers to stop the expansion, which is a key concern of his constituents. As a key Brexiteer in the cabinet, Mr May has tried to allow Mr Johnson to maintain his opposition to the project without breaching today’s whipped vote on it. The prime minister let him leave the country on foreign office business in Afghanistan so that he could avoid voting against the project. His absence did not go unnoticed, however, instead attracting derision from fellow Conservatives and Labour MPs alike. Opposition leader Jeremy Corbyn said: “If he is unable to be present, then we have to ask the question: 'What on earth is he doing and who is he representing?'” Another member of the Conservative government, Greg Hands, resigned as international trade minister last week rather than break an election promise to oppose Heathrow's expansion. He has pointedly tweeted: "Great to arrive back in the UK at Luton Airport in time for the match today and to vote against #Heathrow expansion tomorrow. I wouldn't want to be abroad for either of those. #commitments." Justine Greening, a former cabinet minister whose Putney constituency is on the flight path of Heathrow, responded to Mr Hands with a calculated barb at the foreign secretary: “Great you’re back Greg! I wouldn’t want any long term MP campaigners against #Heathrow expansion to miss their chance to represent their community. #commitment #bulldozer”