# The Identity Cards Act 2006 (Application and Issue of ID Card and Notification of Changes) Regulations 2009, Paragraph 18


(1) In the case of an applicant—
(a) who claims to be a British citizen, but not a citizen of a British Overseas Territory;
(b) who does not currently hold a valid United Kingdom passport describing the applicant as a British citizen;
(c) who was not born or adopted in the United Kingdom;
(d) who was born before 1st January 1983; and
(e) whose father was a British citizen at the time of the applicant’s birth,
the applicant’s passport on which the applicant first entered the United Kingdom and either:
(i) the applicant’s birth certificate in a form which contains details of the parents, if issued by a British consulate or High Commission, or
(ii) the other documents specified in sub-paragraph (2).
(2) The other documents specified for the purposes of sub-paragraph (1) are –
(a) the applicant’s birth certificate not being a certificate issued by a British consulate or High Commission, in a form which contains details of the parents of the applicant, in so far as they are included on the relevant register;
(b) the applicant’s father’s birth certificate or their certificate of registration or naturalisation; and
(c) the applicant’s parents’ marriage certificate .

---
Source: https://www.legislation.gov.uk/ukdsi/2009/9780111480427/schedule/1/paragraph/18 (the official version)
Page: https://openlegislation.uk/draft-identity-cards-act-2006-application-and-issue-of-id-card-and-notification-of-changes-regulations-2009/schedule-1/paragraph-18
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.