(1)If any citizen of the United Kingdom and Colonies of full age and capacity who is also(a)a citizen of any country mentioned in sub-section (3) of section 1 of this Act or of Eire; or(b)a national of a foreign country, makes a declaration in the prescribed manner of renunciation of citizenship of the United Kingdom and Colonies, the Secretary of State, shall cause the declaration to be registered; and upon the registration, that person shall cease to be a citizen of the United Kingdom and Colonies :Provided that the Secretary of State may withhold registration of any such declaration if it is made during any war in which His Majesty may be engaged by a person who is a national of a foreign country.
