"You have heard me sing of a hero bold, Mulcahy was his name, And, faith, he had a sister, too, that was noted for her fame." Kate Mulcahy is tall, red-haired, and apparently unmarried at 28; she cooks at a boarding house
As it stands in Dean, nothing much happens in this song, which seems to be about an old maid. Possibly the singer is courting her to get her money? But Dean's version has only two verses; I suspect a Stage Irish song; either Dean has forgotten some of the lyrics, or they made sense in the context of the drama.
For more on the story, see the notes to "Mulcahy's Gone Away." - RBW