In the case of a trade mark registered before the coming into force of this Act, the foregoing provisions of this Chapter shall not apply by reason only of its consisting of or containing a design or wording which reproduces or resembles an emblem or designation specified in clause (b) or clause (c) of section 12; and where a person is charged with using such a design or wording for any purpose and it is proved that he used it otherwise than as, or as part of, a trade mark so registered, it shall be a defence for him to prove--
         (a) that he lawfully used that design or wording for that purpose before the coming into force of this Act; or
         (b) in a case where he is charged with using the design or wording upon goods, that the design or wording had been applied to the goods before he acquired them by some other person who had manufactured or dealt with the goods in the course of trade and who lawfully used the design or wording upon similar goods before the coming into force of this Act.