(1)Regulations under section 20 must be framed so that any provision made by them—
(a)has effect only for a period not exceeding six months, or
(b)applies only in relation to circumstances occurring in a period not exceeding six months.
(2)This does not prevent further regulations under section 20 from—
(a)making the same provision for, or applying in relation to, subsequent periods (not exceeding six months at a time);
(b)extending (by up to six months) the period for or in relation to which earlier regulations under that section apply.
(3)The Secretary of State must keep regulations under section 20 under review during the period for which they have effect or in relation to which they apply.
(4)If on such a review the Secretary of State is satisfied that that period—
(a)is longer than expedient for the purpose for which the regulations were made, or
(b)has ceased to be proportionate to that purpose,
the Secretary of State must by regulations under this subsection revoke or amend the regulations as appropriate.
(5)Regulations under subsection (4) may contain transitional provision or savings.