by Alan McGuinness

The government is trying to delay a decision on an airport in Medway until after the next election in 2015, according to Boris Johnson.

The London Mayor claims the coalition is trying to appease the “ideological environmental wing” of the Conservative and Liberal Democrat parties.

Mr Johnson, who has been personally pushing an airport in the Towns for years, is worried the idea of building a third runway at Heathrow is increasingly being seen as a potential solution to the country’s impending aviation crisis.

This, he warns, would give the government “the most powerful shock” and he would “die in a ditch” fighting against it.

In an interview with BBC’s Newsnight programme, the freshly re-elected Mayor said: "Let me explain what is happening. They are trying to long-grass it [a Thames Estuary airport]. Their whole strategy is that this is simply too difficult.

"It's difficult because they are trying to appease their ideological environmental wing - some of them in the Tory party some of them in the Lib Dem Party.

An aerial image of the Thames Hub airport, designed by Lord Foster

“They want to keep every ball in the air until past 2015. That's the strategy as far as I understand.”

He admitted an airport in Medway would take 15 to 20 years to build, and said there should be expansion close to London in the interim – such as extra runways at Stansted or Gatwick.

He said: "In reality, you're probably looking at 15-20 years. That's with a certain amount of electro-convulsive shock therapy to the whole thing.

"If we had a bit of get up and go we'd do it in six years. That's how quickly we did it in Hong Kong."

He added: "You should not exclude the possibility of a clean, green, eco-friendly 24-hour hub airport. Conveniently located down river. Offering the chance to entrench this city's lead as the greatest economic commercial capital in Europe.”

Last weekend one of Mr Johnson’s top advisers admitted the project would “very likely” require a substantial amount of money from the government to get it off the ground.

Aviation adviser Daniel Moylan said the money would be needed to fund the infrastructure surrounding an airport.

A DfT spokesman said: "The mayor is right to underline the broad political consensus against a third runway at Heathrow and the government agrees with him that working out the next steps in maintaining our hub status is crucial.

"That is precisely why we are publishing a call for evidence this summer which is all about establishing how we remain connected and competitive for the long term."