The proprietor of the feu shall be entitled to redeem a feu-duty, constituted in terms of the immediately preceding section of this Act, at any term at which such feu-duty is payable on giving three months' previous notice in writing to the superior, and making payment or tender to him of a sum equal to the amount of such feu-duty multiplied by twenty-five, and on such payment or tender the superior shall be bound at the expense of the proprietor to discharge all right to the feu-duty so redeemed, and such discharge (which may be in the form set forth in Schedule C. to this Act annexed, or in a similar form), being recorded in the appropriate register of sasines at the expense of the proprietor, shall operate as a valid and effectual discharge of such feu-duty: Provided always that when the superior shall have granted a heritable security affecting the superiority no discharge to be granted to the proprietor of the feu so redeeming shall be effectual without the consent of the creditor in such heritable security.