Where any one or more of sections 18, 23 to 27 and 30 above apply in relation to a transfer of value but the transfer is not wholly exempt—
any question as to the extent to which it is exempt or, where it is exempt up to a limit, how an excess over the limit is to be attributed to the gifts concerned shall be determined in accordance with sections 37 to 40 below; and
section 41 below shall have effect as respects the burden of tax.