An authorised officer of a local housing authority may at any reasonable time, on giving 24 hours' notice of his intention to the occupier and producing, if so required, some duly authenticated document showing his authority, enter premises for the purpose—
If it is shown to the satisfaction of a justice of the peace on sworn information in writing that there is reasonable ground for entry into premises for any of the purposes mentioned in subsection (1) and—
he may, by warrant under his hand, authorise the authority by any authorised officer to enter the premises, by force if need be.
A warrant shall not be issued unless the justice is satisfied either—
An authorised officer entering premises by virtue of this section, or of a warrant issued under this section, may take with him such other persons as may be necessary; and on leaving any unoccupied premises which he has entered by virtue of such a warrant shall leave them as effectually secured against trespassers as he found them.
A warrant granted under this section continues in force until the purpose for which the entry is necessary has been satisfied.