I haven't heard "Oh, Charlie is my darling" for years and definitely belongs to my childhood. At that time in the 1940's, it could often be heard on radio, generally sung in a classical manner by contraltos and certainly not as a folk song. Indeed I've never heard a Scotsman or Scotswoman of my acquaintance sing it.
When wanting to further my Scottish repertoire, I waded through
Lieder, Songs und Gospels 1 coming up with this song as well as
The World must be coming to an end. The gay lilting tune is somewhat at odds with the implied seriousness of the lyrics.