Subject to the provisions of this section, the rating authority may at any time make such amendments in a rate (being either the current or the last preceding rate) as appear to them necessary in order to make the rate conform with the enactments relating thereto, and in particular may—
Where the effect of the amendment would be either—
the rating authority shall not make any amendment of the rate unless either the amendment is necessary to bring the rate into conformity with the valuation list or a proposal for a corresponding alteration to the valuation list has been made by the valuation officer; and if effect, or full effect, is ultimately not given to such a proposal, and the amount of the rate levied in pursuance of the amendment is affected, the difference—
In the foregoing provisions of this section (other than subsection (1)(c)(i)) references to a rate shall be construed as references to that rate as it has been applied in relation to particular hereditaments; and every amendment made under paragraph (a) or (b) of subsection (1) of this section shall have effect as if it had been contained in the rate as first applied in relation to the hereditament in question or, as the case may require, as first amended in respect of that hereditament under paragraph (c) of that subsection.