For the purposes of any alteration of a valuation list to be made under Part V of this Act in respect of a hereditament in pursuance of a proposal, the value or altered value to be ascribed to the hereditament under section 19 of this Act shall not exceed the value which would have been ascribed thereto in that list if the hereditament had been subsisting throughout the year before that in which the valuation list came into force, on the assumptions that at the time by reference to which that value would have been ascertained—
(a) the hereditament was in the same state as at the time of valuation and any relevant factors (as defined by subsection (2) of this section) were those subsisting at the last-mentioned time ; and
(b) the locality in which the hereditament is situated was in the same state, so far as concerns the other premises situated in that locality and the occupation and use of those premises, the transport services and other facilities available in the locality, and other matters affecting the amenities of the locality, as at the time of valuation.
In this section, the expression " relevant factors " means any of the following, so far as material to the valuation of a hereditament, namely—
(a) the mode or category of occupation of the hereditament ;
(b) the quantity of minerals or other substances in or extracted from the hereditament; or
(c) in the case of a public house, the volume of trade or business carried on at the hereditament;
and in paragraph (c) of this subsection the expression " public house " means a hereditament which consists of or comprises premises licensed for the sale of intoxicating liquor for consumption on the premises where the sale of such liquor is, or is apart from any other trade or business ancillary or incidental to it, the only trade or business carried on at the hereditament.
References in this section to the time of valuation are references to the time by reference to which the valuation of a hereditament would have fallen to be ascertained if this section had not been enacted.
This section does not apply to a hereditament which is occupied by a public utility undertaking and of which the value falls to be ascertained on the profits basis.
This section shall not apply to any proposal remaining to be settled which was served on or made by the valuation officer before 3rd December 1965; and the provisions of Schedule 2 to this Act shall have effect where a proposal in respect of a hereditament was—
(a) served on or made by the valuation officer on or after 3rd December 1965; and
(b) settled before 13th December 1966.