Subject to subsection (2), a person who immediately before commencement—
was a citizen of the United Kingdom and Colonies; and
had the right of abode in the United Kingdom under the Immigration Act 1971 as then in force,
shall at commencement become a British citizen.
A person who was registered as a citizen of the United Kingdom and Colonies under section 1 of the British Nationality (No. 2) Act 1964 (stateless persons) on the ground mentioned in subsection (1)(a) of that section (namely that his mother was a citizen of the United Kingdom and Colonies at the time when he was born) shall not become a British citizen under subsection (1) unless—
his mother becomes a British citizen under subsection (1) or would have done so but for her death; or
immediately before commencement he had the right of abode in the United Kingdom by virtue of section 2(1)(c) of the Immigration Act 1971 as then in force (settlement in United Kingdom, combined with five or more years’ ordinary residence there as a citizen of the United Kingdom and Colonies).
A person who—
immediately before commencement was a citizen of the United Kingdom and Colonies by virtue of having been registered under subsection (6) of section 12 of the 1948 Act (British subjects before commencement of 1948 Act becoming citizens of United Kingdom and Colonies) under arrangements made by virtue of subsection (7) of that section (registration in independent Commonwealth country by United Kingdom High Commissioner); and
was so registered on an application under the said subsection (6) based on the applicant’s descent in the male line from a person (“the relevant person”) possessing one of the qualifications specified in subsection (1)(a) and (b) of that section (birth or naturalisation in the United Kingdom and Colonies),
shall at commencement become a British citizen if the relevant person was born or naturalised in the United Kingdom.