Subject to the provisions of this section, every person born within the United Kingdom and Colonies after the commencement of this Act shall be a citizen of the United Kingdom and Colonies by birth :
Provided that a person shall not be such a citizen by virtue of this section if at the time of his birth—
(a)his father possesses such immunity from suit and legal process as is accorded to an envoy of a foreign sovereign power accredited to His Majesty, and is not a citizen of the United Kingdom and Colonies; or
(b)his father is an enemy alien and the birth occurs in a place then under occupation by the enemy.