London mayor says there is "no evidence" expanding Heathrow would be cheaper than building new hub

London mayor Boris Johnson has outlined his plans for a new London airport to boost the UK’s air capacity as the country falls "further and further behind" in the global aviation race: a four-runway hub on the Isle of Grain as proposed by architect Lord Foster.

Speaking at a press conference, Johnson proposed the inner estuary hub as an alternative to an expansion of Heathrow. He said the government should also consider his original pet project, an outer estuary airport designed by Gensler and dubbed "Boris Island", and an expansion of Stansted airport in Essex as other options.

Johnson said the Isle of Grain plan has some slight advantages, situated near the London Gateway - a deepwater port and logistics hub on the north bank due to open in December - and with its potential for close links to the capital - the plan includes a new train line that would take passengers into Waterloo in 26 minutes. However, he has not yet given up on Boris island.

The London mayor has been a vocal opponent of expansion at Heathrow. He said Britain's largest airport is limited by noise, pollution and congestion and that there is "no evidence" a third or fourth runway at Heathrow would be cheaper than a new hub.

The Isle of Grain project would cost around £65bn, would support 375,000 jobs by 2050, and eventually cater for 180m customers per year. Under current plans, the airport would open in 2029. But speaking to BBC Radio Kent, Huw Thomas of Foster and Partners said that the project could take just seven years from the first shovels in the ground to completion.

For the alternative argument on why we should expand Heathrow, here's Mark Bostock's take in City A.M.