7Any question whether any, and if so what, tax is repayable or ceases to be payable by virtue of subsection (1)(a) of section 149 of this Act in a case where—
(a)the donor's transfer was before a reduction, and
(b)the donee's transfer is after that reduction (or after that and one or more subsequent reductions),
shall be determined as if the Tables in Schedule 1 as substituted by that reduction (or by the most recent of those reductions) had applied to the donor's transfer; but this paragraph shall not be construed as affecting the amount of tax which, under subsection (3) of that section, falls to be taken into account in calculating the cancelled value.