(1)  Subject to section 242  –

(a) an authorised officer who has a reasonable belief that there is or has been on, or in connection with, any premises any contravention of this Act may enter those premises at any reasonable time without notice for the purpose of ascertaining whether in fact there is, or was, any such contravention; and

(b) an authorised officer may enter premises at any reasonable time for the purpose of exercising his or her powers under section 240 .

(2)  On entering and on leaving the premises, an authorised officer must ensure that they are as effectively secured against trespassers as he or she found them.