Had Róisín herself not indicated as much, I was about to say that she sings the song more or less as she heard it from Robert Cinnamond and there should not be any debate over the 'proper words'. Nowithstanding its origin, the authority over the words and air of a song in oral tradition are those of the singer; how else could we have such disparate 'versions'. This is argued as follows in my essay 'About songs and singers' in my website http://moulden.org

<
So, songs change. Above, I’ve described this as being the result of sense being lost. I’m not comfortable with the idea that changes are positive or negative. I don’t think it’s fair to attribute to ignorance, or incompetence, what seems to someone like me, who knows what the song was like in one place, a change, however confused it may seem, in another. If the song has moved to the new community and fixed there, then that’s the way it works in the new place. Besides, if nobody knows how the song was sung before – the song as it’s sung now, is the song. I think that changes to songs most often occur when sense needs to be re-imposed because, due to the song being moved to a new locality, or into a new time frame, meaning has been lost. The song and its community context must be congruent.

That’s really all I know – songs are sung, move from person to person, from one community to another, and they change, the song in one community becomes the song in a different community, the differences between the two do not make one superior. Most interestingly for an obsessional like me, those changes represent differences of mentality – but that’s irrelevant to most other people.>>