12.—(1) Subject to paragraphs (2) and (3), every non-automatic weighing machine shall be made in accordance with a pattern in respect of which a certificate of approval is in operation.
(2) The marking of a machine in accordance with the requirements of regulation 16(2) after it has been made in accordance with such a pattern shall not in itself be a breach of paragraph (1).
(3) Nothing in paragraph (1) shall apply to a machine of the type known as “common form” which was first stamped before 1st August 1991.