29B. Subject to the provisions of this Act, where a signature on a promissory note, bill of exchange or cheque is forged or placed thereon without the authority of the person whose signature it purports to be, the forged or unauthorised signature is wholly inoperative, and no right to retain the instrument or to give a discharge therefor or to enforce payment thereof against any party thereto can be acquired through or under that signature, unless the party against whom it is sought to retain or enforce payment of the instrument is precluded from setting up the forgery or want of authority: Provided that nothing in this section shall effect the ratification of an unauthorised signature not amounting to a forgery.