Parliamentary defeats are like buses: you wait ages for one, and then several turn up at once. The government’s announcement that it will push ahead with building a third runway at Heathrow has people salivating over the possibility of a tricky vote for Theresa May. There are also questions being asked about Labour’s position. The opposition is badly split on the issue, with the major unions largely supportive, and west London MPs – including the shadow chancellor John McDonnell – as well as the party’s committed environmentalists opposed.
There’s no question that the runway is going to cause a degree of political embarrassment to the Prime Minister. Her Foreign Secretary, Boris Johnson, will be conspicuously absent from the vote, and the vote will be loudly and aggressively criticised by almost all her remaining London MPs. It’s also a serious political headache for any ambitious Conservative minister who might want to run for London mayor at some point in the future as there is no path to the London mayoralty for a Tory candidate that does not run through the prosperous parts of west London where opposition to the third runway is at its strongest. That makes it even more difficult to see how some of the candidates tipped for the nomination – like James Cleverly – can plausibly make a decent fist of challenging Sadiq Khan in 2020.
But while the vote is going to have some serious repercussions for the Conservative Party and very probably for the 2020 London mayoral race, regardless of how Labour comes down on the third runway, the actual vote will be inconsequential, because of three simple letters: S, N, and P. The Scottish National Party is pro-third runway and they have 35 MPs – more than enough to mean that even if the Labour party votes en bloc against expansion, there aren’t enough Tory rebels to go around. That the DUP are also longstanding supporters of Heathrow expansion further inoculates the government against any rebellions.
That’s also a handy reminder that for all that while it’s very easy to criticise Heathrow expansion as an infrastructure project “for London”, the reality is that Heathrow is an infrastructure project opposed in London that will be enacted thanks to the votes of MPs from outside the capital.