20:-

(1) A citizen of the United Kingdom and Colonies who is such by registration (including a person registered under subsection (6) of section twelve of this Act) or is a naturalised person shall cease to be a citizen of the United Kingdom and Colonies if he is deprived of that citizenship by an order of the Secretary of State made under this or the next following section.

(2) Subject to the provisions of this section, the Secretary of State may by order deprive any such citizen of his citizenship if he is satisfied that the registration or certificate of naturalisation was obtained by means of fraud, false representation or the concealment of any material fact.

(3) Subject to the provisions of this section, the Secretary of State may by order deprive any such citizen of the United Kingdom and Colonies who is a naturalised person of that citizenship if he is satisfied that that citizen

(a) has shown himself by act or speech to be disloyal or disaffected towards His Majesty; or

(b) has, during any war in which His Majesty was engaged, unlawfully traded or communicated with an enemy or been engaged in or associated with any business that was to his knowledge carried on in such a manner as to assist an enemy in that war; or

(c) has within five years after becoming naturalised been sentenced in any country to imprisonment for a term of not less than twelve months.