20. For regulation 32(2)(b)(ii) substitute—
“(ii)includes 1st April of any calendar year, the value of A in the previous quarterly period adjusted by the percentage increase or decrease, for the calendar year ending on 31st December immediately preceding that 1st April, in—
(aa)the retail prices index, if the tariff start date is earlier than 1st April 2016; or
(bb)the consumer prices index, if the tariff start date is on or after 1st April 2016,
the resulting figure being stated to two decimal places and rounded.”.