Boris Johnson suggests island airport on the Thames

London mayor Boris Johnson has floated the idea of replacing Heathrow with an island airport in the Thames.

Nicknamed ‘Boris Island’ the four-runway airport would be built on an artificial platform made of landfill near the Isle of Sheppey and cost between £10 and £30bn.

It would be connected to London by a 35 minute high speed rail link and be able to operate 24 hours a day because planes would fly over water, limiting noise pollution.

According to the Daily Mail, a review has been completed and engineers are now looking into its feasibility.

But Labour has hit out at the proposal, suggesting Johnson is trying to detract from the Conservative party’s divisions over the future of Heathrow.

The Department for Transport said previous studies had shown an island airport would be more expensive than adding a runway to another airport.

It would also cause environmental problems and pose a threat to high density bird populations, according to the Financial Times.