The airport, most likely to be located on an artificial island off Sheppey in Kent, would have four runways, but capacity for two more if required and would be connected to the Channel tunnel rail link.
Johnson’s aides believe the scheme, loosely modelled on Hong Kong International Airport, could take just six years to build, eventually leading to a phased closure of Heathrow and possibly even Gatwick.
The Heathrow site, which employs 70,000 workers, could ultimately be turned into Britain’s equivalent of Silicon Valley, with technology parks and aff ordable homes.
