Where any question affecting the operation in relation to imported goods of an order under section 1 of this Act depends on the country in which they were grown, produced or manufactured or on that from which they were consigned to the United Kingdom, the Commissioners of Customs and Excise may require the importer of the goods to furnish to them, in such form as they may require, proof of any statement made to them as to any fact necessary to determine that question ; and if such proof is not furnished to their satisfaction, the question may be determined without regard to that statement.