Hi Martin,
Brendan O Dowda, an expert on Percy French, claims that French admitted using "Carrigdhoun" as a template for "The Mountains of Mourne" However, it seems very likely that whoever set music to Denny Lane's poem, "Carrigdhoun," used Moore's "The Bendemeer Stream". The big question is, where did Moore get it. Most of Moore's melodies were adapted from traditional tunes.
See you in Inishowen