Was his first name different too ?
The man I looked into whole family seemed to revert to mothers maiden name for a few years
Including the children !
There was some story about them having to hide ...
Hi,
I had something similar occur. My g grandfather joined the army using his mother's maiden name.(Beside his enlistment, the records for the birth of his chldren whlst in the army states that he is using is an alias. It also gives his real name.) In my g grandfather's case, I guess the reason my. G grandfather used an alias to join the army was down to to his father's past.
His father committed suicide. It was a small town, type of place where everyone knew each other, doubled with he carried an uncommon name, so people would have known he was related to his father with the same surname. His father was also x army.
Apparently, for many years before his father comitted suicide, he was a bit of a nut job (threatened to kill his wife on many occasions, wife eventually kicked him out) . I have hard records detailing all this, statments from wife ot inquest, army records, births and not family hearsay (it was covered up in my family until I uncovered it. It all came a bit of a shock to my family)
So yes, with a surname change ,he may be hiding something, or from someone,or it may be for a perfectly good reason.
The Op's g grandfather is a first name change ,it seems (?). It could be for any numerous reasons,from something he wanted to cover up to down to he didn't like his birth Christian name (I had an aunt who did this). He even may be using his middle name (as known by name to family and friends)on some of the records. I have plenty of those in my family, using middle names as first names too.
There could be any one of numerous reasons for an alias, without knowing any background or details of Newbie2017s g grandfather
Kind regards:)
Ps for the record my g grandfather who used an alias in the army was not Irish.
Please exuse typos , I am using my phone