Right you are, Mark!  I'm so used to people doing things like that and really meaning it (and believing that they've actually "improved" a song in the process) that I rather missed the humour intended.  Oh well.  As to the identity of the recording you heard, Nic Jones and Chris Foster would both be good bets; if the accompaniment was solo guitar, perhaps Jones, if it was fiddle (played by Jones, as it happens) then Foster (who had the higher voice).  Muckram Wakes recorded it in the middle '70s, too, but that was a duet accompanied by guitar and free-reed of some sort.