13E+W+SWhere—
(a)any sum was deposited with an Electricity Board by way of security under any provision of the Electricity Acts; and
(b)on and after the day appointed for the coming into force of any provision of Part I of this Act that sum is treated by the Board as deposited under that provision of that Part,
any period beginning three months or less before that day, being a period during which the sum was deposited with the Board, shall be treated for the purposes of the payment of interest on that sum as a period during which the sum was deposited under that provision of that Part.