4. For paragraph (3) of regulation 6 (earnings periods for earnings to be aggregated where the earnings period for those earnings would be of different lengths) substitute—
“(3) In this regulation “the designated earnings period” means—
(a)where the earnings are derived from employments which include any contracted-out employment and any non-contracted out employment, the earnings period in respect of earnings derived from the contracted-out employment or, if there is more than one such employment, the shorter, or as the case may be the shortest, of the earnings periods in respect of earnings derived from such employments; and
(b)in any other case, the shorter, or as the case may be the shortest, of the earnings periods in respect of the earnings derived from such employments.”.