There used to be quite a few conservative folkies about (it wasn't just you, Branno, I'd almost forgotten that). As specified in my thesis, I felt Colin Dryden was one of the best singers, guitarists, voice there was.
When Folksongs get altered, the best bits, the reason we like the song and want to sing it, stay pretty much the same. The essence remains. There's no reason to get too excited about changes (although people do), especially when we have so many examples preserved in print and actual recordings of the author. If we want to speak of definitive versions, or originals etc., then transcripts of Dryden's recordings have to be a starting point.
If people feel they want to tweak the lyrics or tunes to keep the song alive through another era or region, well that's what makes it a folksong. The more versions, the greater the song.