The Minister may recover as a debt due to the Crown any expense incurred under section 160A or 160B--
(a) from any person who without lawful authority erected or placed or was, immediately before its removal, maintaining the structure concerned on prescribed land or who caused it to be so erected, placed or maintained, or
(b) from any person who has made use of the structure after the expiration of the period specified in a notice prohibiting use of the structure--(i) served on the person under section 160F, or(ii) displayed on or adjacent to the structure under that section (but, in such a case, only if it is proved that the person knew, or ought reasonably to have known, about the notice).