Can anyone help, Please

My fathers' half-brother, James Scullion, born c1901 (+/- 1), was born to my Gran. 'out of wedlock' and, I presume adopted. I suppose it's possible Scullion was the name of my Grans' boyfriend ?
Catherine Mckeown, my Gran, later moved from near Moneymore, to Glasgow where she married my Granda.
I know, from relatives, Jimmy had visited her in glasgow, but the only information that survives is an address in 'Ballsbridge, Dublin'.
I've no idea what he worked at, and as far as I know, he never married.
Any suggestions to where I can start a search, would be great,
regards, Charlie.