Northolt at top of these photos listing 107 aerodromes within 50 miles of Hyde Park Corner. Same file and close in date to above. "Caxton Gibbet" would be a great name for a London Airport. ( last photo ).
https://www.nasa.gov/feature/faq-the-international-space-station-2022-transition-plan A big factor - the avoidance of Basildon.... https://www.distance.to/Basildon/Ducie-Island,PCN
Choose another place on the map from February 1959 ( TNA ref AIR2/14333 ) which shows population around Blackbushe, Heathrow, Stansted and Southend.
Interesting to see the extent of Bullingdon Rural District on there... Bullingdon - Wikipedia Bullingdon Rural District - Wikipedia Bullingdon Club - Wikipedia HM Prison Bullingdon - Wikipedia Bullingdon Hundred - Wikipedia
A large target. London Terminal Control Area, 1958 ( TNA ref AIR2/14333 ): looks like aircraft routeing along Amber or Green should look out for a "UFO" from NASA.