lex soli: By birth in the UK or a qualified British Overseas Territory to a parent who is a British citizen at the time of the birth, or to a parent who is settled in the UK or that Overseas Territory lex sanguinis: By birth abroad, which constitutes "by descent" if one of the parents is a British citizen otherwise than by descent (for example by birth, adoption, registration or naturalisation in the UK). British citizenship by descent is only transferable to one generation down from the parent who is a British citizen otherwise than by descent, if the child is born abroad. By naturalisation By registration By adoption