Where payment on account of a debt or of interest on a legacy is made before the expiration of the prescribed period by the person liable to pay the debt or legacy or by his agent duly authorised in this behalf, a fresh period of limitation shall be computed from the time when the payment was made:
         Provided that, save in the case of payment of interest made before the 1st day of January, 1928, an acknowledgment of the payment appears in the handwriting of, or in a writing signed by, the person making the payment.
         Explanation.—For the purposes of this section,—
             (a) where mortgaged land is in the possession of the mortgagee, the receipt of the rent or produce of such land shall be deemed to be a payment;
             (b) "debt" does not include money payable under a decree or order of a court.