The nationality law in force at the time of her birth, and indeed when she first came to Britain, was the British Nationality and Status of Aliens Act 1914. Section 1 of that Act says:
"1 Definition of natural-born British subject
(1) The following persons shall be deemed to be natural-born British subjects, namely :—
(a) Any person born within His Majesty's dominions and allegiance; and
(b) Any person born out of His Majesty's dominions whose father was, at the time of that person's birth, a British subject, and who fulfils any of the following conditions, that is to say, if either—
(i) his father was born within His Majesty's allegiance; or
(ii) his father was a person to whom a certificate of naturalization had been granted; or
(iii) his father had become a British subject by reason of any annexation of territory; or
(iv) his father was at the time of that person's birth in the service of the Crown; or
(v) his birth was registered at a British consulate within one year or in special circumstances, with the consent of the Secretary of State, two years after its occurrence, or, in the case of a person born on or after the first day of January, nineteen hundred and fifteen, who would have been a British subject if born before that date, within twelve months after the first day of August, nineteen hundred and twenty-two; and
(c) Any person born on board a British ship whether in foreign territorial waters or not."
The Dominions were defined in the first schedule of the Act as: The Dominion of Canada, The Commonwealth of Australia (including for the purposes of this Act the territory of Papua and Norfolk Island), The Dominion of New Zealand, The Union of South Africa, and Newfoundland.