In message , Tom
Anderson writes

Also, there's a copy of a map from the 1944 Abercrombie London
masterplan, mostly detailing the layout of the green belt, but it shows
the locations of airports. I recognised Heathrow, Northolt (i think)
and the one down near Croydon, but there was also one shown to the
east, within the M25, north of the river (i think - i didn't make an
exact note). Any idea what that might be?

Undoubtedly Fairlop, which had been earmarked as a replacement for
Croydon long before Abercrombie.

In fact (and to tie-in with another recent thread here) I've long
suspected that the rather extraordinary idea of projecting the Central
Line round the little-used Fairlop loop came about because London
Transport had its eye on potential airport traffic after the war.

During the 1930s the LCC battled with the Crown Commissioners on the
purchase of Fairlop Plain, which the former wanted for housing but the
latter wanted to retain as open space for "uses such as golf or
aviation". The Greater London Regional Planning Commission (and, I
think, the Air Ministry) supported the use of the land for an aerodrome.
Abercrombie marked Fairlop Plain as one of four principal airport sites
to serve London, the others being Croydon, Heston (i.e. Heathrow) and
Potter Bar.

But eventually the war, and then the green belt, intervened - and so
Fairlop never did become the major London airport that was once
envisaged.
--
Paul Terry