4E+WIf a sub-mortgage by assignment of a term is subsisting immediately before the commencement of this Act, the principal mortgagee shall take the principal derivative term created by paragraphs 1 or 2 of this Part of this Schedule or the derivative term created by his mortgage (as the case may require), and the sub-mortgagee shall take a derivative term less by one day than the term so vested in the principal mortgagee, subject to a provision for cesser corresponding to the right of redemption subsisting under the sub-mortgage.