Sch 3 para 4F
(1) A senior officer may— (a) cancel an authorisation with effect from a time identified by the officer concerned; (b) substitute an earlier date or time for the specified date or time; (c) substitute a more restricted area or place for the specified area or place. (2) Any such cancellation or substitution in relation to an authorisation confirmed by the Secretary of State under paragraph 4D does not require confirmation by the Secretary of State.