A bit about Harold Boulton: later Sir Harold E Boulton, editor of many song compilations for which he provided some song words - including "Songs of the North" and "Songs of the Four Nations." He was author of such songs as "The Skye boat song" and "The Lough Tay boat song" which were set to arrangements of traditional Scottish tunes.

So far my inquiries give no hint as to when or under what circumstances he wrote "The castle of Dromore" - but his being almost a professonal song writer indicates that his songs don't have to be about any place he knew at all.