‘BORIS Island’ has been rejected by aviation chiefs as too expensive and economically harmful.

The Thames Estuary Airport proposal, strongly backed by the Mayor of London, was turned down by the Airports Commission today.

Had the four-runway superhub on the Isle of Grain opposite Southend been accepted, it would have led to the closure of Southend, City and Heathrow airports.

Commission chairman Sir Howard Davies said it recognised the need for a new hub but that it should be part of a competing network of airports.

He said: “The economic disruption would be huge and there are environmental hurdles which it may prove impossible, or very time-consuming to surmount."

He also cited cost as a reason for rejecting the scheme as, at £70-90 billion for the least ambitious scheme, it far outstripped any other proposal.

Boris Johnson, the Mayor of London, maintained the idea was “not dead” but was quick to express his disappointment.

He said: "In one myopic stroke the Airports Commission has set the debate back by half a century and consigned their work to the long list of vertically filed reports on aviation expansion that are gathering dust on a shelf in Whitehall.”