Section 240 of the Act of 1947 (which empowers rating authorities to levy rates on owners, instead of occupiers, in certain cases) shall not authorise the retention by a rating authority of any portion of a rate paid by an owner under that section in respect of any period during which the lands and heritages concerned are unoccupied; and accordingly in that section for the words “fails to recover the amount payable by any such occupier” there shall be substituted the words “is unable to recover the amount paid by him to the rating authority”.