harrym and Ian B-B
Re your mention about flying boats in Karachi. There was some discussion here on PPRuNe a few years ago about Empire Flying Boats to the Far East.
As an aside can I point you to a brilliant read here on PPRuNe by a "PPRuNer" (Flatus Veteranus) who flew from Poole Harbour to Rangoon, Burma (Myanmar) in the Short C (Empire) Class flying boat Caledonia in 1940 including a night stop at Karachi.
It is a wonderfully descriptive account of what flying in a flying boat was all about. Here:
http://www.pprune.org/aviation-histo...caledonia.html