18. It shall be a defence for any person charged with an offence relating to accompanying documentation under regulation 13 or 14 to prove—
that the consignment received was part of a larger consignment which was consigned to another address:
that the batch had, so far as he was aware, the correct documentation at the time of delivery; and
that he believed that the documentation would be delivered to the point of final destination of the last part of the batch.