hello again, I have followed up on the advise I received re Sgt. Byrne. I have his death cert and it states he died from what appears a heart attack at home and is recorded as an army pensioner. I also have his daughters (my aunt) birth cert and he is recorded as an ex soldier, 1908. Trying to figure out how he is recorded as a Casualtie of WW1 and buried in Grangegorman Military Cemetery (CWGC)
I can't locate him in the 1901/1911 Irish Census but there is a Private John Byrne born Dublin in the 1901 UK census, Topsham Artillery Barracks. The connection I make here is that Clonmel Barracks was a base for the Royal Field Artillery and he lived around the corner from it in King St at the time of the birth of his daughter.