Thanks for that.
BNA 48 s12 states:
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;
Citizenship by birth
Subject to the provisions of this section, every person born within the United Kingdom and Colonies after the commencement of this Act shall be a citizen of the United Kingdom and Colonies by birth :
I read this as saying that as my wife's father was born in the UK before the commencement of the act, he was a British subject by birth and he would be a CUKC in 1948 under s12 because of the alleviation under s4.
I cannot see anywhere in BNA48 anything that defines the UK post 1922.
I understand that 'citizenship by descent' can only handed down for one generation. Either my father-in-law handed down CUKC status to my wife, or, because he was born in Ireland (when part of the UK), he gained CUKC from his father who was born in Liverpool. I could understand the latter if my father-in-law had been born after 1922 as Ireland would then not be part of he UK. I do not understand how a person born in the UK to British parents looses natural nationality status. It would be the same for someone born in Cardiff or Edinburgh!
So, did BNA48 remove the British subject status from my father-in-law and hence require him to adopt CUKC by descent? If so, my wife has no case for CUKC. If it didn't, then she should have CUKC status by descent from her father.
I apologise if this is becoming protracted.