5.—(1) This article applies for the purposes of article 4(1).
(2) Whether or not a licence-holder is a member of a group with another licence-holder is to be determined on the date referred to in article 4(1).
(3) Where under paragraph (2) a licence-holder is a member of a group with another licence-holder, the amount of electricity or, as applicable, gas supplied by the group in the year ending on the date referred to in article 4(1), is the amount supplied by those licence-holders whether or not they were members of the group throughout that year.