“(4A) (a) A requirement under subsection (4) of this section may be made of a person either personally or in a notice in writing served upon him by registered post.

(b) Notwithstanding the said subsection (4), where a requirement under that subsection is made of a person in a notice served upon him by registered post the person shall not be guilty of an offence unless he fails to comply with the requirement within the time (being not less than 14 days from the date on which the notice was posted) specified in the notice.”.