Presumptions of prosecutions for contraventions of order made under section

3 or section 4.— In a prosecution for an offence for the contravention of an order made under section 3 or section 4 on the production of an authentic copy of the order, it shall, until the contrary is proved by the accused, be presumed—

1. (a) that the order was made by the authority competent under this Act to make it;
2. (b) that the authority making the order was satisfied that the grounds on, or for the purpose for which it was made existed, and that it was necessary to make the same; and
3. (c) that the order was otherwise valid and in conformity with the provisions of this Act.