s 30C ... section 30A: supplemental
(1) A person who has been required to attend a police station is not required to do so if he is given notice in writing that his attendance is no longer required. (2) If a person is required to attend a police station which is not a designated police station he must be— (a) released, or (b) taken to a designated police station, not more than six hours after his arrival. (3) Nothing in the Bail Act 1976 applies in relation to bail under section 30A. (4) Nothing in section 30A or 30B or in this section prevents the re-arrest without a warrant of a person released ... under section 30A if , since the person’s release, new evidence has come to light or an examination or analysis of existing evidence has been made which could not reasonably have been made before the person’s release .