Citizenship from Father born New Zealand 1936?

[portrower]

My partner was born in the US in 1974. Her father was born in New Zealand in 1936. Her father's father was born in the UK circa 1905.

Her father, now deceased, had a UK passport. We don't know if he was a citizen by descent (via his father) or otherwise than by descent (by virtue of being born in New Zealand before the Nationality Act of 1948). Is there a way to determine this?

It seems as though if his citizenship was by descent, she cannot claim UK citizenship, but if it was otherwise than by descent she can?

Thanks for any help!

[secret.simon]

Impressive research. Kudos to you for knowing of the British Nationality Act, 1948.

The father, born in New Zealand, was a CUKC (later a British citizen) by descent. He does not seem to meet the requirements of Section 12(1), but does meet the requirements of Section 12(2) of the British Nationality Act 1948. Subsection 8 of that Section lists people acquiring CUKC status under subsection 2 as being CUKC by descent only.

British subjects before commencement of Act becoming citizens of United Kingdom and Colonies
(1)A person who was a British subject immediately before the date of the commencement of this Act shall on that date become a citizen of the United Kingdom and Colonies if he possesses any of the following qualifications, that is to say—
(a)that he was born within the territories comprised at the commencement of this Act in the United Kingdom and Colonies, and would have been such a citizen if section four of this Act had been in force at the time of his birth;
(b)that he is a person naturalised in the United Kingdom and Colonies;
(c)that he became a British subject by reason of the annexation of any territory included at the commencement of this Act in the United Kingdom and Colonies.

(2)A person who was a British subject immediately before the date of the commencement of this Act shall on that date become a citizen of the United Kingdom and Colonies if at the time of his birth his father was a British subject and possessed any of the qualifications specified in the last foregoing subsection.
...
(8)A male person who becomes a citizen of the United Kingdom and Colonies by virtue only of subsection (2), (4) or (6) of this section shall be deemed for the purposes of the proviso to subsection (1) of section five of this Act to be a citizen of the United Kingdom and Colonies by descent only.

That status carried over under the British Nationality Act 1981 (Section 14(1)(b)(ii)).

14 Meaning of British citizen (by descent).
(1)For the purposes of this Act a British citizen is a British citizen “by descent” if and only if—
...
(b)subject to subsection (2), he is a person born outside the United Kingdom before commencement who became a British citizen at commencement and immediately before commencement—
...
ii)was a person who, under any provision of the British Nationality Acts 1948 to 1965, was deemed for the purposes of the proviso to section 5(1) of the 1948 Act to be a citizen of the United Kingdom and Colonies by descent only, or would have been so deemed if male; or

[portrower]

Thanks secret.simon for the very thorough reply. Not the answer we were hoping for, but I appreciate your help!