3. A person who establishes to the satisfaction of the Revenue Commissioners that he has borne or paid tax on the supply to or importation by him of hydrocarbon oil used for combustion in the engine of a sea-fishing vessel in the course of a sea-fishing business carried on by him and who fulfils to the satisfaction of the said Commissioners the conditions which are specified in paragraph 4 of this Order, shall be entitled to be repaid the amount of tax so borne or paid.