This is the seventh decade in which south east runway capacity has been debated, enquired about, reported on, ideas floated, commissions etc etc etc. Still no extra runway!!
Interesting to consider what has happened at Amsterdam, Paris, Frankfurt etc airports during this time. Moreover population growth and general development in the south east [particularly west of London] during the last seventy years has rendered development of runways at existing airports significantly more problematical.
Boris Island is ambitious and futuristic. Yes there are lots of problems, costly yes, but none are insurmountable........didn't they do something like that in Hong Kong? The Foulness solution proposed by the Roskill Commission could have been in service for years by now!
As someone said earlier, we'll probably still be debating it in ten years!