The simple fact is that LHR is in the wrong place and any of the alternatives in the southeast are inaccessible to most of the nation.
There is a solution which has not been given due consideration - build a complete new airport near BHX with 6 runways. Alter the route of the proposed HST link to pass through (under) the terminal and add motorway spurs from the M5 and M42. This can easily be financed by selling LHR to property developers who would rent the site to the existing user until the new airport is complete and then cover the site in nice expensive housing. Travel time from Paddington to this new airport by HST would not be much different to the existing rail route to LHR so not a problem.
LGW then becomes a regional airport for the southern part of the southeast with LTN serving those north of the thames.
Sorted.
Last edited by The Ancient Geek; 11th Dec 2015 at 14:20.
Reason: spelling