The Japanese built Kansai in 7 years, (1987-1994). It's in one of the most seismically active areas of the Earth's surface. When the Olympics are over next year, GB will need another big project to work on. So, let's get started on London-Thames-Boriswick.
If we can't build an airport in the relatively benign geological environment of the Thames estuary, quicker than Kansai or a railway line, it's a poor show. We have folks unemployed and a downturn in aviation in which to do it.