Thames Estuary airport would provide 'thousands more jobs'
An airport in the Thames Estuary would support 336,000 jobs and contribute £92.1bn to the economy each year by 2050, according to the Mayor of London.
The Airports Commission is considering whether Boris Johnson's proposal for the Isle of Grain should be on its shortlist of airport expansion options.
It would mean more than five times as many jobs than if Gatwick expanded and a third more than Heathrow, he said.
Opponents have described the proposal as "environmental vandalism".
But Mr Johnson said the options came down to "planning for the future" or "depressing short-termism".
Releasing the figures in a last-ditch bid to persuade the commission to support his proposal, Mr Johnson said: "A new hub airport, properly planned, has the potential to reshape the economic geography of London and the whole of the South East for decades to come.
"It would be a project of a scale we are no longer accustomed to in this country, though it has become commonplace elsewhere.
"We simply cannot afford to miss out on the opportunities a new airport would give us."
'Waste of money'
The commission is due to make a decision on the proposal next month.
The Isle of Grain is located on the Hoo Peninsula in north Kent and is almost all marshland.
It is home to many thousands of wintering birds and other wildlife leading the RSPB to describe the proposal as "disastrous".
Experts have predicted it could cost up to £2bn to provide alternative habitats for the wildlife.
Rodney Chambers, leader of Medway Council, said the location was "financially, geographically and environmentally wrong".
"It will waste tens of billions of pounds of taxpayers' money for a project which is on the wrong side of London for the majority of passengers," he said.
The Airports Commission has so far shortlisted three options, which include adding a third runway at Heathrow, lengthening an existing runway there, and a new runway at Gatwick.
A Heathrow spokesperson said: "The Mayor of London has said that Britain definitely needs a successful hub airport if it is to compete in the global race. This leaves two choices: expand Heathrow or build a new solution in the Thames Estuary.
"A new Thames Estuary option is estimated to cost more than £100bn, while expanding Heathrow can connect the UK to growth more quickly at a fraction of the cost."
Support from businesses
Gatwick's chief executive officer Stewart Wingate said the West Sussex airport was "the obvious choice" for additional runway capacity.
"It is deliverable and affordable, and is the best option for passengers.
"Expanding Gatwick would allow Heathrow to get better but not bigger, creating two world-class airports in London that would compete to provide more connections to the rest of the world and better customer service," he said.
The mayor's report was released as a survey by the Kent Invicta Chamber of Commerce found that a four-runway estuary airport was strongly supported by the Kent business community.
Hundreds of businesses responded indicating support for a new airport was three times the level of that for an expanded Heathrow.
There was also about a third more support than plans for a new runway at Gatwick.