7. The amount of tax to be repaid in accordance with paragraph 3 or reclaimed in accordance with paragraph 5 shall, subject to paragraph 8, be the tax borne or paid which the qualifying person shows to the satisfaction of the Revenue Commissioners to be referable solely to outlay which relates to—

(a) the construction, extension, alteration or reconstruction of that part of the building or structure which was designed solely for the purposes of a farming business and has actually been put to us in such a business carried on by him, or

(b) the fencing, drainage or reclamation of any land which has actually been put to use in such a business carried on by him.