The Argonaut was of course an uprated DC4/Skymaster, with UK (Rolls Royce) engines, pressurisation, etc, and built in Canada, all to circumvent the critical shortage of US Dollar foreign exchange. They served BOAC particularly well and stood in for a range of supposedly better UK-built types over the years that followed.
I can't find a single Skymaster/C-54/DC4 in a production list of them which operated for the RAF. Didn't Churchill use a Liberator for major foreign visits ?