Notwithstanding anything contained in any law for the time being in force, in a prosecution for an offence for the contravention of an order made under section 46, section 47 or section 48 on the production of an authentic copy of the order, it shall, until the contrary is proved by the accused, be presumed—
         (a) that the order was made by the authority competent under this Act to make it;
         (b) that the authority making the order was satisfied that the grounds on, or the purpose for, which it was made existed, and that it was necessary to make the same; and
         (c) that the order was otherwise valid and in conformity with the provisions of this Act.