5.—(1) An arbitrator appointed in accordance with paragraph 3(1) to (4) or 4 shall conduct the arbitration in accordance with this Schedule and shall base his award on findings made by him as to areas used for milk production in the last five-year period during which production took place before the change of occupation, or, in the case of a prospective apportionment, in the last five-year period during which production took place before the appointment of the arbitrator.
(2) An arbitrator appointed in accordance with paragraph 3(5) shall conduct the arbitration in accordance with this Schedule and shall base his award on findings made by him as to the areas used for milk production in the last five-year period during which production took place before the appointment of the arbitrator.
(3) An arbitrator appointed under any paragraph of this Schedule shall base his award on findings made by him in accordance with the law in force at the time the event giving rise to an application for arbitration took place.