Hi. My great grandfather was married in Fermoy, Cork in 1904. His address on his marriage cert is New Barracks, Fermoy and profession is Private Soldier. His name on the marriage certificate is Percy O'Brien. Just to confuse things, his name on the birth cert of his 3 children is Pierce O'Brien. He moved to the UK around 1930. I am unable to find him in any military records using either name nor in any census records in Ireland or the UK. His father's name was James but I am unable to find a link using his name either. I have used Ancestry but am currently on Find My Past but neither have shed any light. Can anyone suggest any other paths I can follow to try to find him?