The British Dependent Territories Citizenship (Designated Service) Order 1982

1.  Service in pursuance of an appointment outside the dependent territories in respect of which the person concerned is on secondment from Crown service under the government of a dependent territory. For this purpose, a person is on secondment from Crown service under the government of a dependent territory if, having been serving in such Crown service, he is for the time being in temporary service under arrangements whereby he is to return to such Crown service when that temporary service ends.