Sorry I'm 12 years late to the party. I want to know if "The shepherd's wife"/"O shepherd, O shepherd" shares a common ancestor with the Spanish ballad "La gentil dama y el rústico pastor". Both song-types are in dialogue form, with the woman offering a series of inducements and the shepherd (it's always a shepherd) offering a series of refusals. It's been floating around Spain since the 15th century as far as anybody knows.