Here is a photo of the Upper deck of our Sandringham at Solentsky Museum in Southampton, UK. she was origninally built as a 1943 Sunderland III. I took it about 2 weeks ago, come along and you can explore her to imagine the era.
It sounds to me like the original post was describing a much more luxurious C-Class. They were in use throughout the war as passenger planes and were, of course kept as clear as possible from any hostilities.
Cheers
Trevor