Designated hereditaments
21.—(1) The central valuation officer shall from time to time alter each list, whether prospectively or retrospectively, to conform with–
(a)regulations under section 53 of the Act, and
(b)subject to paragraph (2), relevant orders.
(2) If at any time it appears to the central valuation officer that a relevant calculation is likely to result in an alteration, he may alter the list to give effect to the rateable value which in his opinion that calculation will produce.
(3) An alteration under paragraph (2) shall have effect from the day from which the alteration to give effect to the rateable value produced by the relevant calculation would have effect in pursuance of the relevant order.
(4) For the purposes of this regulation–
a “relevant calculation” is a calculation falling to be made in respect of a description of designated hereditaments in pursuance of a relevant order; and
a “relevant order” is an order under paragraph 3(2) of Schedule 6 to the Act.