The northern connection as asserted by Tim connects "Clan Owen" with Tyrone. The Tyrone connection is more likely to Owen O'Neill and Owen O'Donnell, Lords in that area in the 16th 17th centuries. At least one of them marched to Kinsale and took part in the Flight of the Earls.
Clan Owen is quite reasonably situated in the South and may derive from Owen Roe O'Sullivan .
All this from my wives remembrances of her history lessons.
The Castle of Dromore at Kenmare is on the Blackwater and was built in the very late 19th century by a tennis player (who's name escapes me)and who was the only Irishman to win the men's singles at Wimbledon (in about 1893 or thereabouts)
Just because it is a fairly recent castle does not mean it could not be the castle of the song. Has anyone thought of checking any connection between Boulton and the castle's builder? My son will be at Dromore next week and I have asked him to send me any info he can get