The Certification Officer may appoint one or more members of his staff or other persons as an inspector or inspectors to investigate the financial affairs of a trade union and to report on them in such manner as he may direct.
The Certification Officer may only make such an appointment if it appears to him that there are circumstances suggesting—
Where an inspector is, or inspectors are, appointed under this section it is the duty of all persons who are or have been officials or agents of the trade union—
Where any person (whether or not within subsection (3)) appears to the inspector or inspectors to be in possession of information relating to a matter which he considers, or they consider, to be relevant to the investigation, the inspector or inspectors may require him—
and it is the duty of the person to comply with the requirement.
In subsections (3) and (4) "relevant documents", in relation to an investigation of the financial affairs of a trade union, means accounting documents, and documents of any other description, which may be relevant to the investigation.
A person shall not be excused from providing an explanation or making a statement in compliance with subsection (3) or a requirement imposed under subsection (4) on the ground that to do so would tend to expose him to proceedings for an offence; but an explanation so provided or statement so made may only be used in evidence against the person by whom it is provided or made—