I recall that we had a somewhat lively discussion on the location of the castle portrayed in the song. Given its popularity and its potential as a tourist draw, several locations in Ireland have been quick to claim it as 'theirs'.
Certainly the Kenmare location is a natural conclusion, given that it rests alongside the Blackwater River. However, during our exploration we discovered that the name Blackwater applies to numerous rivers throughout Ireland; indeed, there are also multiple castles named Dromore, or locations named Dromore that contain castles.
Our conclusion at the time (though by no means a consensus decision) was that the castle just might be a metaphorical castle IN (the district of) Dromore, as opposed to a specific castle named Dromore. The reference to Clan Owen and the fact that Boulton was known to have visited the north suggests that his inspiration was spawned there.
I personally like the concept of the conclusion that the castle is a magic and imaginary one! It's appearance is whatever you envision when you sing or hear those lyrics. 'Great song... one of my favourites!
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