"The following must produce to the Immigration Officer a valid passport or other identity document endorsed with a United Kingdom entry clearance issued to him for the purpose for which he seeks entry: (i) a visa national; (ii) any other person (other than British Nationals (Overseas), a British overseas territories citizen, a British Overseas citizen, A British protected person or a person who under theBritish Nationality Act 1981 is a British subject) who is seeking entry for a period exceeding six months or is seeking entry for a purpose for which prior entry clearance is required under these Rules. Such a person will be refuse leave to enter if he has no such current entry clearance. Any other person who wishes to ascertain in advance whether he is eligible for admission to the United Kingdom may apply for the issue of an entry clearance."