Proof of content etc. of Commissioner etc.

Whenever under this Act or any rule, regulation or bye-law made thereunder the doing of or the omission to do anything or the validity of anything depends upon the approval, sanction, consent, concurrence, declaration, opinion or satisfaction of the Commissioner or of any Corporation officer a written document signed by the Commissioner or officer purporting to convey or set forth such approval, sanction, consent, concurrence, declaration, opinion or satisfaction, shall be sufficient evidence thereof.