For historical context, this was a fairly common thing: before 1949, the then British empire had a common citizenship and most* people born in any colony were citizens of the whole. https://en.wikipedia.org/wiki/British_subject. Those people all got stripped of their British nationality as their countries became independent, and then Britain went on to strip that nationality from all the other (non-white) people in countries that they *did* continue ruling, like Hong Kong.
* Not Indians who were subjects of the indirectly ruled "princely states" which covered a large chunk of India. Probably not Egyptians, given that Britain was nominally suzerain there.