Sch 4 para 2
(1) If it is shown to the satisfaction of a justice of the peace on complaint on oath— (a) that there are reasonable grounds for the exercise in relation to any premises of a relevant power; and (b) that one or more of the conditions specified in sub-paragraph (2) is fulfilled in relation to those premises, the justice may by warrant authorise an authorised person to exercise the power in relation to those premises, in accordance with the warrant and, if need be, by force. (2) The conditions mentioned in sub-paragraph (1)(b) are— (a) that the exercise of the power in relation to the premises has been refused; (b) that such a refusal is reasonably apprehended; (c) that the premises are unoccupied; (d) that the occupier is temporarily absent from the premises and the case is one of urgency; or (e) that an application for admission to the premises would defeat the object of the proposed entry. (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (4) Every warrant under this Schedule shall continue in force until the purposes for which the warrant was issued have been fulfilled.