I think that it is good that Traditional music is constantly evolving. Its part of the Oral Tradition where songs may be misheard, as like Chinese whispers, over time we end up with several variants of an original song or ballad. Ron Kavana certainly add some words but kept to an old tradition. Who knows how far back this tune goes? It was probably taken to the US by British Emigrants in the 18th or 19th centuries. Its a lovely tune though.