(1)No post-war refund shall be made to any person unless such undertakings and authorities are given as are specified in the next following section, being undertakings and authorities in connection with the use of the net amount of the refund for the purposes of a specified trade or business, being such-a trade or business as is mentioned in subsection (2) of this section:
Provided that undertakings and authorities may be given as aforesaid in connection with the use of part only of the said amount and shall, if so given, operate to authorise the payment of-a corresponding part of the refund, and references in this and the three next folio wing, sections td the refund and the net amount of the refund shall be construed accordingly.
(2)A trade or business may be specified under subsection (1) of this section if it is either—
(a)the original trade or business; or
(b)a trade or business carried on or to be carried on by the person who carried on the original trade or business in the relevant chargeable accounting periods, or, where that person is an individual, by him or by a relative of his; or
(c)a trade or business in which the said person, or, where the said person is an individual, he or a relative of his, has or is to have an interest which is substantial in relation to the size of the trade or business:
Provided that in considering whether the interest of a person in a trade or business is substantial, any interest acquired by or for him in consideration of the making over, to the persons who are carrying on or are to carry on that trade or business, of the whole or any part of the post-war refund in question shall be left out of account.
In this subsection, the expression " a relative " means, in relation to a person, that person's husband or wife, or a son, daughter, brother or sister of that person or of that person's husband or wife or deceased husband or deceased wife, and for the purposes of this definition the expressions " son " and " daughter " include an adopted son or adopted daughter (whether adopted under the [16 & 17 Geo. 5. c. 29.] Adoption of Children Act, 1926, or under the [20 & 21 Geo. 5. c. 37.] Adoption of Children (Scotland) Act, 1930, or otherwise) and an illegitimate son or illegitimate daughter, and the expressions " brother " and " sister " include a half-brother or half-sister.
(3)A trade or business shall be treated for the purposes of this and the three next following sections as continuing to be the same trade or business notwithstanding, any change in the persons carrying it on.