United Kingdom - Passport & Nationality - British Overseas Territories Citizen (BOTC 12(5) PGF)
This route to British citizenship relies on a paternal grandfather's birth in a British Overseas Territory. If this is coupled with a parent's birth before 1 January 1949 and their own birth in the period 1 January 1949 to 31 December 1982, it gives the candidate the ability to register as a British Overseas Territory Citizen (or BOTC) and then upgrading this to full British nationality.
The territories that make up this group of British Overseas Territories are: Anguilla, Bermuda, British Virgin Islands, Cayman Islands, Falkland Islands, Gibraltar, Indian Ocean Territory (Chagos), Montserrat, Pitcairn Islands, South Georgie and South Sandwich Islands, St Helena, Ascension, Gough and Tristan da Cunha, and the Turks and Caicos.