§ 19. "That the enactments relating to the National Defence Contribution shall have effect and be deemed always to have had effect subject to such Amendments as will secure that, in the case of the businesses mentioned in sub-paragraph (a) of paragraph 7 of the Fourth Schedule to the Finance Act, 1937, any income received from investments or other property is taken into account in computing the losses to be carried forward under sub-paragraph (1) of paragraph 2 of that Schedule, notwithstanding that that in come has been separately charged to Income Tax by deduction or otherwise."