As to Alice comment and note above, I appreciated the quote from Hughes, since I never found out where to get the 4th volume. [Hughes, however, seems to have expurgated some of his songs, so didn't give us the real folksongs. "The Stuttering Lovers" is an example of which I've found the 17th century version.]

It seems to me obvious there is no 'one' correct version a traditional tune. A traditional tune is just that, a traditional tune. There are a few instances where it seems that someone didn't record the tune of a traditional singer or player correctly, and only in such a case do I think there is a basis for saying the tune isn't a correct 'traditional' tune. But all really traditional tunes are correct traditional tunes, even if they aren't the 'original' tune for the song. [It has been argued by some competent musicologists that 'Londonderry Air' wasn't noted down correctly; it's just too unlike any other known Irish air, and possible corrections have been suggested.]