If, at any time after the end of the period of twenty-one days beginning with the day on which a planning contravention notice has been served on any person, he has not complied with any requirement of the notice, he shall be guilty of an offence.
An offence under subsection (1) may be charged by reference to any day or longer period of time and a person may be convicted of a second or subsequent offence under that subsection by reference to any period of time following the preceding conviction for such an offence.
It shall be a defence for a person charged with an offence under subsection (1) to prove that he had a reasonable excuse for failing to comply with the requirement.
A person guilty of an offence under subsection (1) shall be liable on summary conviction to a fine not exceeding level 3 on the standard scale.
If any person—
he shall be guilty of an offence.
A person guilty of an offence under subsection (5) shall be liable on summary conviction to a fine not exceeding level 5 on the standard scale.