(1) The powers of the Director under section 2 are also exercisable for the purpose of enabling him to determine whether to start an investigation under section 1.

(2) But -

(a) the power under subsection (2) of section 2 is so exercisable only if it appears to the Director that for the purpose of enabling him to make that determination it is expedient to require any person appearing to him to have relevant information to do as mentioned in that subsection, and

(b) the power under subsection (3) of that section is so exercisable only if it appears to the Director that for that purpose it is expedient to require any person to do as mentioned in that subsection.

(3) Accordingly, where the powers of the Director under section 2 are exercisable in accordance with subsections (1) and (2) above -

(a) the reference in subsection (2) of that section to the person under investigation or any other person whom the Director has reason to believe has relevant information is to be read as a reference to any such person as is mentioned in subsection (2)(a) above,