text: **3.**—(1) A person who is a Crown servant, a government contractor, or a member of a visiting 
  
  force, who— 
  
  (a) is required to undertake work necessary to the delivery of essential defence activities; 
  (b) has travelled from a point of origin within the common travel area or from a category 1 
  country or territory on a vessel or aircraft operated by, or in support of, Her Majesty’s 
  armed forces or by, or in support of, a visiting force and that vessel or aircraft has not 
  taken on any persons, docked in any port or landed in any category 2 country or territory; 
  or 
  
  (c) has undertaken a continuous period of at least 10 days ending with the day immediately 
  preceding the day of their arrival in the United Kingdom aboard a vessel operated by or in 
  support of Her Majesty’s Naval Service or by, or in support of, a visiting force, where 
  they have not disembarked and that vessel has not taken on any persons or docked in any 
  port outside of the common travel area for a period of at least 10 days ending with the day 
  of its arrival in the United Kingdom. 
  (2) For the purposes of sub-paragraph (1)— 
  
  (a) “defence” has the meaning given in section 2(4) of the Official Secrets Act 1989; 
  (b) “visiting force” means any body, contingent or detachment of the forces of a country, 
  being a body, contingent or detachment for the time being present in the United Kingdom 
  (including United Kingdom territorial waters), on the invitation of Her Majesty’s 
  Government in the United Kingdom. 