(1)An authorisation under section 44 has effect, subject to subsections (2) to (7), during the period—
(a)beginning at the time when the authorisation is given, and
(b)ending with a date or at a time specified in the authorisation.
(2)The date or time specified under subsection (1)(b) must not occur after the end of the period of 28 days beginning with the day on which the authorisation is given.
(3)The person who gives an authorisation shall inform the Secretary of State as soon as is reasonably practicable.
(4)If an authorisation is not confirmed by the Secretary of State before the end of the period of 48 hours beginning with the time when it is given—
(a)it shall cease to have effect at the end of that period, but
(b)its ceasing to have effect shall not affect the lawfulness of anything done in reliance on it before the end of that period.
(5)Where the Secretary of State confirms an authorisation he may substitute an earlier date or time for the date or time specified under subsection (1)(b).
(6)The Secretary of State may cancel an authorisation with effect from a specified time.
(7)An authorisation may be renewed in writing by the person who gave it or by a person who could have given it; and subsections (1) to (6) shall apply as if a new authorisation were given on each occasion on which the authorisation is renewed.