A person is exempt for the purposes of this section if he is exempt from provisions of this Act as a result of section 8(2) or (3).
If a person who is exempt—
ceases to be exempt, and
requires leave to enter or remain in the United Kingdom as a result,
he is to be treated as if he had been given leave to remain in the United Kingdom for a period of 90 days beginning on the day on which he ceased to be exempt.
If—
a person who is exempt ceases to be exempt, and
there is in force in respect of him leave for him to enter or remain in the United Kingdom which expires before the end of the period mentioned in subsection (2),
his leave is to be treated as expiring at the end of that period.
References in this section to a person who ceases to be exempt do not include a person who ceases to be exempt by virtue of section 8B(3).