Cure of defective disentailing assurance

Where a person entitled in remainder to an entailed interest in any land has made an assurance thereof which fails to bar the issue in tail or the estates and interests taking effect on the determination of the entailed interest, or fails to bar the last-mentioned estates and interests only, and any person takes possession of the land by virtue of the assurance, and that person or any other person whatever, other than a person entitled to possession by virtue of the settlement, is in possession of the land for a period of twelve years from the commencement of the time at which the assurance, if it had then been executed by the person entitled to the entailed interest, would have operated, without the consent of any other person, to bar the issue in tail and such estates and interest then, at the expiration of that period, the assurance shall operate, and be deemed always to have operated, to bar the issue in tail and those estates and interests.