Tam Kearney (Fiddlers Green FC Toronto) told the story told to him by Ewan McColl how he heard a Canadian lumberjack singing a McColl song and swore it was taught to him by his Gran. The timespan was only a few years, but one can speculate it was emminently plausable.
The story goes on that Ewan requested more "songs from Gran" and elecited "Please Release me Let me Go". Which would date the story to late 60's early 70's. McColl was looking for "Trad songs"

Which demonstrates what has been said many times above. Close communities, in making their own entertainment, know little of the wider context and to a young boy/adolescent the provenance is far less important than the content. And memory being what it is .............

Surely we are skirting Mondegreen territory here.