Thanks to the above I have dug out the details of the C-54 Skymasters with the RAF, whose existence I was attempting to deny. It would have helped if I had computer-searched my source for them, not as "RAF", but as "Royal Air Force", which is how they were listed
Most of them seem to have been with the RAF in India around 1945, transferred from the USAF, and later transferred back maybe 12 months later using the same USAF tail numbers as before, which sort of points to a loan arrangement rather than actual purchase. There were just a handful which look to have made it to European bases.