If it appears to a local authority that any works are urgently necessary for the preservation of any unoccupied building situated in their area which—
is included in a list compiled or approved under section 54 of this Act; and
is not an excepted building as defined in section 58(2) of this Act,
they may, after giving to the owner of the building not less than seven days' notice in writing of the proposed execution of the works, take such steps as they consider appropriate for executing the works.