A public sector agency that holds personal information must take such steps as are, in the circumstances, reasonable to enable any person to ascertain--
(a) whether the agency holds personal information, and
(b) whether the agency holds personal information relating to that person, and
(c) if the agency holds personal information relating to that person--(i) the nature of that information, and(ii) the main purposes for which the information is used, and(iii) that person's entitlement to gain access to the information.