British Citizen applying for oci

Hello everyone,
I'm looking for some help.
My mother is trying to apply for an OCI card.
She is a British citizen who was born in India. One of the questions on the OCI form is asking how she became a British citizen.
She was born in India in 1941 and immigrated to Kenya under her mother's passport in the 1950s. Her first ever passport was issued in 1960 and states that it's a British passport (Colony and Protectorate of Kenya).
In 1965 she immigrated to the UK and has been here ever since.
She also has the normal burgundy British passport.
From an OCI application perspective She has nothing to show how she became a British citizen I.e she doesn't have a netualisation or registration certificate.

Does she actually need to provide evidence considering she was a part of a colony and Protectorate of Kenya.?

Any advise or guidance would be appreciated.

Thanks

Sups

There are 6 types of British nationality. Does her passport definitely state she is a British citizen?

Hi, Ohara

Absolutely, on the front cover it says "British passport's and then in the 1st page, under national Status it says "British subject: Citizen of the united Kingdom and colonies"

You don't seem to have read what I wrote.

British Subject is a different form of British nationality, which is specifically why I asked. It is not the same as British citizenship.

This is a complex area of the law and one that I am not an expert in, so you will need to wait for someone with more knowledge to answer.

What year was her British passport issued?

Hi again..
Oh right I see.. it was issued on the 5th Dec 1960.