Parent Irish Citizen, FBR or Naturalisation?

[SterileBacteria]

So have come into a conundrum, my father is a Irish citizen who was born abroad (in the UK) in 1966 and had a valid Irish passports derived from his parents since then as well as UK ones, however he doesn't have any information relating to Foreign births registrations and said that when he applied for his passport this wasn't required, he just applied for it. We are assuming he is a citizen of Ireland despite being born abroad, but are unsure as to now if his son (myself) wants to apply for Irish citizenship, what route do we go down? FBR asks for the registration number (which he doesn't have) and naturalisation also asks for info that he doesn't have.

As far as we can tell he is a Irish citizen so not sure what the next steps would be to pursue it other than applying for a Irish passport directly.

Any thoughts on this would be appreciated.

[Vorona]

Your father most likely was registered in FB registry by his parents. Just because your father doesn't have his FBR certificate, it doesn't mean he never had it. It might have been lost. He needs to get a replacement from Department of foreign affairs and trade.

If you were born abroad, you will also need to be registered in foreign birth registry. You will not be able to apply for an Irish passport unless you get registered first.

[littlerr]

What’s your father’s parents’ nationality, and where were they born?

Your father would not need an FBR if one of his parents was born on the island of Ireland.