You may have to give us some more details for us to advise you correctly.
Presumably your mother acquired CUKC status from her father. What was her father doing in Rwanda and when (month/year) and where was the father born? Also, where and when was her mother born (that is not relevant for CUKC status, but for RoA status)?
As a rule of thumb, British citizenship can only be passed on one generation outside the UK. Assuming that her father (your grandfather) was not in Crown Service in Rwanda (such as a diplomat or military staff posted there by the British government), your mother herself would have been a British citizen by descent and so would have been unable to pass on British citizenship to you automatically.
Belleee wrote: ↑Fri Aug 22, 2025 12:22 am
given her long residence in the UK
That may affect her RoA status, but it won't have affected her CUKC status.
There is where the confusion between her being a British citizen by descent and her being a BOC likely arose. If she had not resided in the UK for at least five continuous years before 1983, she would have most likely become a BOC.
Essentially a CUKC with RoA became a British citizen on 1st January 1983. A CUKC without RoA became a BOC on that date.
And to become a British citizen otherwise than by descent, the person would have needed to have both a CUKC status not by descent and an RoA status not by descent. Your mother obviously had RoA status not by descent (but by five years residence in the UK). But that didn't change her CUKC status.
Belleee wrote: ↑Fri Aug 22, 2025 12:22 am
the fact that her status was wrongly recorded for years
Irrelevant. Keep in mind that there is no central database where British citizenship is recorded. She would need to keep the records of the basis of her citizenship. All the Home Office does is that when presented the documents, they assess and make a determination of your mother's status. If they assess it incorrectly, based on the documents that she (your mother) provided, she can appeal that assessment and/or reapply with more documents.
The Home Office can be faulted for making incorrect assessments. But the proof of maintaining and providing the documentation lies with your mother (the applicant). The Home Office may have made the correct assessment if she did not provide all relevant documentation.
Belleee wrote: ↑Fri Aug 22, 2025 12:22 am
is there any chance my mother should be considered British otherwise than by descent?
No, because the requirements for being a British citizen by descent or otherwise is spelt out in
Section 14 of the the British Nationality Act 1981 and is not something for a caseworker to decide on with discretion. Either she meets the requirements spelt out by the law or she doesn't.
Belleee wrote: ↑Fri Aug 22, 2025 12:22 am
Her older passports show her as BCUKC under section 5(1) of the BNA 1948
If her older passports explicitly stated as such, your mother is a British citizen by descent under Section 14(1)(b)(i) of the British Nationality Act 1981.
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—
(i)was a citizen of the United Kingdom and Colonies by virtue of section 5 of the 1948 Act (citizenship by descent);
The exception in subsection (2) is based on her father being in Crown Service. So, (a) what was her father's job in Rwanda and (b) do you have documentary proof of that job?
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.