There is a Time article from 1945 that talks about his niece saying it was written for his wife's family butler. It does not say where his wife's family is from and that is an important piece of knowledge.
Anyway, the reason it is such a hard song to give up singing is because it is not only so beautiful, but it is so universal and so iconic and about a portion of the population that does not get many songs written about them..older men on their way out of life.
It is like people wanted us to quit singing Danny Boy..which as a woman I believe I am not supposed to sing so I don't..but think how sad it would be for all those old men who it means so much to..that they want it sung at their funerals etc. Same sort of song.
Oops..every St. Patrick's day we get the message loud and clear we should not be singing Danny Boy as it is corny beyond words..so bad comparison. mg