Ah the nostalgia! My childhood at Prestwick airport was filled on a daily basis with the C-54GMs of the RCAF, the DC-4M2s of Trans Canada Airlines and (less frequently) by the C-4 Argonauts of BOAC.
I think the Newcastle DC-4M2 was CF-TFM which had been bought from TCA by Overseas and which disappeared mysteriously one day to Holland and Czechoslovakia wearing a fictitious Italian registration I-ACOA.
It was flown by the infamous Hank Warton (later of Biafra fame) and ended its life when he ran out of fuel and crashed in northern Cameroon.