I am sure I have seen Seaboard and Western (later Seaboard World) C-46’s at Heathrow in the early 60’s, doing freight runs for ???? I seem to remember a lot of blue smoke issueing from the engines during taxying !
This quote from the Seaboard website.

The Curtiss-Wright C-46 “Commando” was based primarily in Europe, and served as a feeder aircraft connecting Seaboard’s main European stations with smaller, outlying cities. The company operated a number of Commandos over two decades of service, but never more than two at a time.

This photo also from same website.

Keith.