The British Citizenship (Designated Service) (Amendment) Order 1987
Section 2 of the British Nationality Act 1981 provides, inter alia, that a person born outside the United Kingdom after commencement of the Act is a British citizen if at the time of the birth his father or mother is a British citizen and is serving outside the United Kingdom in service designated by the Secretary of State, recruitment for that service having taken place in the United Kingdom. Various types of service are designated for the purposes of this provision by the British Citizenship (Designated Service) Order 1982.