When any instrument of gaming has been seized in any house, room or place entered under section 5 or about the person of anyone found therein, and in the case of any other thing so seized, if the court is satisfied that the Magistrate or police officer who entered such house, room or place had reasonable grounds for suspecting that the thing so seized was an instrument of gaming, the seizure of such instrument or thing shall be evidence, until the contrary is proved, that such house, room or place is used as a common gaming-house and the persons found therein were there present for the purpose of gaming, although no gaming was actually seen by Magistrate or the police officer or by any person acting under the authority of either of them:
Provided that the aforesaid presumption shall be made notwithstanding any defect in the warrant or order in pursuance of which the house, room or place was entered under section 5, if the court considers the defect not to be a material one.