Róisín Dubh is an old song. You will find lyrics and notes at http://www.locrian.com.au/waiting/wait_bk.html
and a translation at Irish love songs

Legend of Róisín Dubh (Dark Rosaleen) includes the following information
"Dark Rosaleen" is a Gaelic poem translated by James Clarence Morgan[sic -should be Mangan] who lived from 1803 to 1849. It is an allegory in which Red Hugh O'Donnell addresses Ireland and calls on the Pope in Rome and King Philip of Spain (late of the Armada) to come to his aid. The call to arms is well concealed in the poem to avoid 'Treasonable Utterances' for which the penalty was death.

Some people say it really is a love song

Sound trackS which I have not personally tried out: singles and Silex lyrics and explanation at http://www.locrian.com.au/waiting/wait_bk.html

Katlaughing should have a look at Cat's laugh