I need some evidence the Peter Buchan printed a version, otherwise it's an interesting theory.
The "Butcher Boy" (similar to Cruel Miller only a butcher boy instead of a miller) is sung by many of the Aberdeenshire travellers including Stanley Robertson, her aunt Jeannie Robertson, Jean Stewart and her daughter Elizabeth (text in Mudcat) -- then Lizzie Higgins - her grandmother etc.
I have 19 versions, there are two that are probably cover songs.