Thanks, Malcolm. That is most interesting and enlightening information.

I once expressed confidence that a Romantic composer would find it nearly impossible to leave a "folk melody" alone when it could be "improved" by a nudge here and there.

Regardless of whether Campbell so treated "The Cuckoo in the Grove," its formal kinship to "Skye Boat Song" is hard to miss.

Worth noting: Campbell was in a boat when she heard the tune. That fact is sometimes transmuted into the claim that the melody was originally a "Scottish sea chantey."