I please need help in the hereafter case.
My very good friend lives in Cape Town - South Africa - since his birth,
which was in 1969.
His father was British, born in 1927 in Liverpool.
His mother was South African.
Both are already dead.
My friend has a "Certified Copy Of An Entry Of Birth" from his father

The parents (grand parents) where Irish, but we have not a small bit of
information about them (except the names and the mother maiden name).
My question is now, is he British?
Is he entiteled to a British passport?
The bad

him, that he is not entiteled to British citizenship, because his father was not married to his mother.
I can't believe this, because what is the difference married or not?
The problem was, that his father and mother where not allowed to marry,
because of problems (apartheid, UK marrying black woman, etc., etc.).
Thank you very much for all help in advance.
Please let me know, if more information is needed.
God bless

Jesus-INN