An airport in the Thames Estuary moved one step closer earlier, with confirmation the government would hold a consultation into the proposals.
Having ruled out expansion at the existing airports in the south of England, government officials are seeking ways to ensure the UK maintains its position as an aviation hub.
However, the idea, championed by London mayor Boris Johnson, still faces many hurdles.
Liberal democrat leader and deputy prime minister Nick Clegg is believed to be opposed to the idea, while environmental campaigners have long attacks the plans, claiming local birdlife would be endangered.
Chancellor of the exchequer George Osborne pointedly did not rule out the plan in 2011 during his Autumn Statement, suggesting to many observers the plan was gaining in support.
As many as 400 million passengers a year are expected to pass through London each year by 2050, according to a report by the Greater London Authority, up from 140 million in 2010.
There is more information on the estuary proposal here.