Wisley as has been stated would never get even a second look because of the rich Nimbys in that area. The problem UK has is that if Boris island is built then there are no airports west of London at all and who is going to travel out to the thames estuary when at the current rate of increase the rail fare would be about the same as a J class ticket to JFK (exageration yes but it makes a valid point)
So where next Blackbushe, Odiham, Lasham, Benson
No, it will be NHT for the short hop over to AMS for onward connections, just like the rest of the country.
Not only would the rail fare to the estuary be "
about the same as a J class ticket to JFK", but complicated and time consuming (about half the time as a flight to JFK, no exageration) as well.
Actually it's an important point that: there would be NO airports west of London, the area where international companies have their European headquarters. Great planning!