If the premises in respect of which a warrant is issued under this Schedule are occupied by a public authority and any officer or employee of the authority is present when the warrant is executed, he shall be shown the warrant and supplied with a copy of it; and if no such officer or employee is present a copy of the warrant shall be left in a prominent place on the premises.

If the premises in respect of which a warrant is issued under this Schedule are occupied by a person other than a public authority and he is present when the warrant is executed, he shall be shown the warrant and supplied with a copy of it; and if that person is not present a copy of the warrant shall be left in a prominent place on the premises.