This is one of those folksongs whose plot doesn’t really hold water. A girl lives with her uncle and loves a ploughboy. The uncle wants her to marry upmarket to a squire and to endear himself to his niece he locks her in her bedroom. The girl is adamant so the uncle arranges to have the pressgang take the ploughboy away. Later the squire tries to force himself on the girl and gets shot by her for his troubles. The uncle tries to intervene and is also shot by the girl. As a dying gesture, he is so impressed with the girl’s spirit that he leaves her all his money in his will and she lives happily ever after.
Personally I find this story quite cranky and doubt whether either Hollywood or Mills and Boon could make anything credible from it. Nevertheless, the song has proved hugely popular and versions of it are still in oral tradition and it is vastly collected throughout the English-speaking world. Is it because singers just like to get their tongue around those resonant syllables at the end of every verse or perhaps the easily remembered tune?
As “Undaunted Mary” the song was often printed on broadsides and nearly always sung in England to the same tune, the same tune used, for example, for “Box on her Head”.