Brabazon Committee
I think the aviation writer Bill Gunston dismissed the US-Transports UK-Combat Types notion as a myth. The C-87 was the transport version of the B-24 Liberator, the first military Constellations were designated C-69
The first DC-4/C-54 was almost complete when Pearl Harbour was attacked and flew 2months later in February 1942, the first Constellation flew in January 1943 (so the design was pretty firm by Pearl harbour)...making them pre-war designs from the US point of view