Welcome to Rootschat

but we need a bit more detail in order to find information for you or suggest where you can look next. This isn't a forum for tracing living relatives since your father is deceased we might be able to help.
When and where did your father die and how old was he then? His death certificate might be helpful.
Did he ever marry? if so, the marriage certificate might list his father's name and occupation
You mention 'Northern Ireland' so you must think he had some connection there. Do you have a more exact location?