5. The enactment or obligation does not prevent or penalise the disclosure of relevant information by contractor A or an employee of his to another Department, Minister, office-holder or district council (“authority D”) or an authorised officer of that authority if—
(a)the disclosure is necessary or expedient for the purpose of facilitating the exercise of the relevant function, a related function or a function of authority D;
(b)the disclosure falls within a description of disclosures certified by authority A (whether in the authorisation or otherwise) to be capable of being so necessary or expedient; and
(c)the information could be lawfully disclosed, for that purpose, by authority A to authority D.