63Building society advances: certain advances not special advances but subject to their own limit
(1)An advance to which this section applies is one made by a building society to a housing association on the security of a freehold or leasehold estate by means of a mortgage where—
(a)immediately before the execution of the mortgage, the Housing Corporation has an interest in the same freehold or leasehold estate under a mortgage entered into by the housing association, and
(b)the security represented by the last-mentioned mortgage is, with the agreement of the Corporation, postponed to the building society's security under the first-mentioned mortgage.
(2)The following advances—
(a)an advance to which this section applies, and
(b)an advance which in accordance with section 21(7) of the [1962 c. 37.] Building Societies Act 1962 a building society is treated as having made by reason of a transfer from one housing association to another, or from a housing association to the Housing Corporation, or from the Housing Corporation to a housing association, of the mortgagor's interest under a mortgage securing an advance made by the building society,
do not constitute special advances as defined by section 21 of the Building Societies Act 1962 and shall not be brought into account under section 22(2)(b) of that Act (ordinary limits on special advances).
(3)A building society shall not in the first financial year in which it makes advances on the security of freehold or leasehold estate make any advances to which this section applies.
(4)In any subsequent financial year a building society shall not, except in accordance with a permission under subsection (5), make advances to which this section applies of a total amount which exceeds 15 per cent. of the total of the advances of all descriptions made by the building society in the last preceding financial year on the security of freehold or leasehold estate.
(5)The Chief Registrar may, if he thinks fit, grant to a building society permission in writing to make advances to which this section applies in excess of the limit imposed by subsection (4), but subject to such other limits as may be specified in the permission.
(6)For the purposes of this section—
(a)" financial year " has the meaning given by section 128 of, and paragraph 11 of Schedule 8 to, the Building Societies Act 1962, subject to paragraph (b) below;
(b)for the purposes of subsection (4) if a financial year is shorter or longer than the last preceding financial year, a corresponding reduction or increase shall be made in the figure of 15 per cent. mentioned in that subsection ; and
(c)section 21(7) of the [1962 c. 37.] Building Societies Act 1962 (deemed advance on transfer of mortgage) applies for the purpose of ascertaining what advances a building society has made in a financial year.