2(1)The period over which repayment is to be made shall be—
(a)25 years, or
(b)where the mortgagor’s interest in the dwelling-house is leashold and the term of the lease is less than 25 years, a period equal to the term of the lease,
or, at the option of the mortgagor, a shorter period.
(2)The period mentioned in sub-paragraph (1) may be extended by the mortgagee.