Plans to expand London's other airports are already further along than Heathrow's and have in the past been viewed as an alternative to a third Heathrow runway. Work is set to start this year to expand capacity at Stansted's terminal. The government is due to make a decision on Gatwick airport by 27 February.

What could a third runway at Heathrow mean for tourism and the climate? Whatever the outcome, it’s still a long way away from happening.

The U.K. government is backing the construction of a third runway at London’s Heathrow Airport, Treasury chief Rachel Reeves said Wednesday in a speech designed to signal to the business world that the new Labour government is serious about turning around the economy.