No prosecution for an offence under this Act, other than an offence under section 10, may be instituted—
(a) without the written consent of the Director of Public Prosecutions, or that of the Attorney General where the prosecution is to be instituted against the Director of Public Prosecution; or
(b) after 5 years from the date when the person in respect of whose declaration on financial affairs the alleged offence was committed, ceased to be a person in public life.