British Citizenship by descent question

[Sandyofili]

Hi everyone . My dad was a British citizen by naturalization. He passed away when I was 3 months old. He was married to my mom and he had me outside the Uk. I’m trying to apply for I’m citizenship by decent but I don’t have any proof that my dad was a I’m citizen. My older half siblings got their citizenship through my dad before I was born. I’m 23 now. How do I go about applying if I don’t have documents proofing his citizenship.

Thank you all.

[vinny]

If your father was naturalised and married to your mother prior to when you were born, then you are automatically British.

Ask your siblings if they still have the documents / evidence that they had used. Perhaps you may use the same?