Regulation 16

If dutiable goods are brought by post into the United Kingdom in any postal packet contrary to Regulation 6 of these Regulations, or if any postal packet or mail bag to which Regulations 7, 8 and 9 of these Regulations or any of them apply does not contain, does not have affixed or attached to it, or is not accompanied by, the declaration, or does not bear the green label, required by those Regulations or any of them, or if the contents of any postal packet do not agree with the green label or customs declaration affixed or attached to the packet, or by which it is accompanied, or if the other requirements of these Regulations or any of them are not complied with in every material respect, then in every such case the postal packet or mail bag and all its contents shall be liable to forfeiture.