My copy of the Reivers is "....grandfather and me..." (Top Rank International – JKR 8026, trk. B1, 1959.) I don't think Top Rank ever put out 78s.
Lonnie Donegan (I Wanna Go Home) did sing it as "grandpappy" for sure but again, dunno about a Canadian 78.
I don't think he was the only one to sing it that way.