The flowchart is to be applied to your mother, since the question is that of whether she has right of abode. You can also apply it to your grandfather though. Please don't misuse the term 'right of abode' - it only applies if you establish that certain specific conditions are met. Having CUKC passport itself does not confer it. Please bear with the long post and details - they really do matter in your case:
CUKC
This came into effect in 1949. Before that, everyone was a British subject; there was no such thing as a British citizen (that was defined in 1983). People living in UK and its remaining colonies had CUKC, while those in independent countries lost CUKC (this applies to my father, born in India shortly before independence). Your grandfather became CUKC by passage of law while in Kenya. Your mother was later born in Kenya and was CUKC for the same reason - Kenya was still a colony.
Both of them retained CUKC in 1963 when Kenya became independent, because several East African countries did not automatically accord CUKCs their own citizenship. Your mother later moved to India
Question: When did she move to India ?
Question: Which years between 1951 and 1983 did she reside *in* UK ?
Right of Abode:
Your grandfather did not have right of abode in 1949. The concept of right of abode was defined in the Immigration Act of 1971 . Before that, anyone with a CUKC passport had ability to go live in UK. So we cannot speak about what he had in 1949, much before the concept existed. In 1971, the law of Right of Abode was established to determine which CUKCs has Right of Abode and which ones did not.
British Nationality Act 1981
This came into effect Jan 1 1983. It got rid of CUKC. Instead, three new classes came into effect:
British citizen
British Dependent Territories Citizen
British Overseas Citizen
There was also British National (Overseas), but that is Hong Kong specific, I believe, so we ignore that. Also, dependent territories is for Gibraltar, Falklands etc, so we ignore that. The choice is between British Citizen and British Overseas citizen.
Anyone with CUKC on Dec 31 1982 was given one of the above statuses. Your mother's choices were:
- *IF* she had Right of Abode as defined by the flowchart, then she gets British Citizen passport
- If she didn't, then she got British Overseas passport.
The latter is what happened. This means that the British government did not recognize that she had Right of Abode on Dec 21 1982, or at any time prior to that date, according to INA 1971. So by consequence she had no Right of Abode when you were born.
What happened in 2002
I believe your mother was one of those affected by this court case:
UK overseas citizens win right to live in Britain
This gave a number of otherwise stateless BO passport holders full British citizenship. That is why your mother got one such passport in 2003. Please read the article - it even refers to Kenya and dovetails with your mother previously getting a BO passport in the 1980s.
Therefore, by all available evidence, your mother did not have Right of Abode at the time you were born. The flowchart questions:
1. Was the claimant a CUKC (see note E) by birth, adoption, naturalisation or registration (see note A) in the UK (see note B)
Answer: No. Your mother was born in Kenya, not UK
2. Was either of the claimant's parents (see note C) a CUKC (see note E) when the claimant was born or legally adopted (see note D)?
Answer: Yes your grandfather was CUKC in 1951
3. Was the parent at that time a CUKC (see note E) by birth, adoption (see note D), naturalisation or registration (see Note A) in the UK (see note B)?
Answer: No. Please prove otherwise - you have indicates nothing to suggest your grandfather was *IN* the UK.
4. Was either of that parent's parents (see note C) when the parent was born or legally adopted (see note D) a CUKC (see note E) by birth, adoption (see note D), naturalisation or registration (see note A) in the UK (see note B)?
Answer: No, since CUKC didn't exist when your grandfather was born (pre 1949).
5. Is the claimant a woman?
Answer: yes, since claimant is your mother here.
6. Was she ever married at any time before 1 January 1983 to a Commonwealth citizen (see note F) who had the right of abode?
Answer: No, since there's no evidence your father has Right of Abode separately.
7. Had the claimant, whilst a CUKC (see note E) been ordinarily resident in the UK (see note B) for 5 years at any time before 1 January 1983, and was he at the end of that period settled here?
Answer: Presumably No. This is why I repeatedly asked - has your mother spend 5 years in UK before 1983, and if so, when ?
The conclusion of this path is: Claimant did not have the right of abode on 31 December 1982.
That is why your mother got a British Overseas passport in 1980s - she did not have the Right of Abode then, i.e. when you were born in India.