51. (1) A person who is, or reasonably believes that he or she is, authorised by this Act to communicate official information to another person shall be deemed for the purposes of section 4 of the Official Secrets Act 1963 to be duly authorised to communicate that information.

(2) In a prosecution for an offence under section 5 or 9 of that Act, it shall be a defence to prove that the act to which the charge of the offence relates is authorised, or is reasonably believed by the person charged to be authorised, by this Act.