§ Where an interest in expectancy within the meaning of Part I. of the Finance Act, 1894, in any property has, before the eleventh day of May, nineteen hundred and fourteen, been bonâ fide sold or mortgaged for full consideration in money or money's worth, then no other duty on that property shall be payable by the purchaser or mortgagee when the interest falls into possession than would have been payable if this Part of this Act had not passed, and in the case of a mortgage any higher duty pay-Able by the mortgagor shall rank as a charge subsequent to that of the mortgagee.