Any declaration having effect immediately before the appointed day with respect to the calorific value within the meaning of the Gas Act 1948 of gas supplied by an Area Board shall, not-withstanding the different meaning given to that expression for the purposes of this Act, have effect as from that day as a declaration of calorific value validly made by the Corporation for those purposes.

Subject to sub-paragraph (3) below, for the purpose of ascertaining the calorific value of gas supplied by the Corporation to any area, the Secretary of State shall be treated as having made on the appointed day a determination under section 25(1) of this Act that the gas supplied to that area is to be treated as containing such an amount of water vapour as is requisite to saturate the gas with water vapour.

Sub-paragraph (2) above shall not apply in the case of gas supplied by the Corporation from any gasworks or group of gasworks in relation to which a direction under section 74(1) of the said Act of 1948 is in force immediately before the appointed day, but, instead, for the purpose mentioned in the said sub-paragraph (2), the Secretary of State shall be treated as having made on the appointed day a determination under the said section 25(1) in relation to that gas having the like effect as that direction or, as the case may require, it shall be assumed as from the appointed day that the Secretary of State has made no such determination in relation to that gas.