Lascaille, follow the link, the additional exemptions are very, very narrow.
I didn’t include it because, in the case in question, the only pertinent exemption is if the child was born out of wedlock. To wit.....
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Born before 1 July 2006 to a British father
You can register as a British citizen if you:
- were born before 1 July 2006
- would have become a British citizen automatically if your parents had been married
- are of ‘good character’ - see the guidance to form UKF for details......