For the purposes of this Part of this Act, the value of an interest in land, or of an interest in so far as it subsists in particular land, shall be taken to be depreciated by a planning decision (in this section referred to as "the relevant decision") if, and to the extent to which, that value, calculated in accordance with the following provisions of this section, falls short of what that value, so calculated, would have been if the relevant decision had been a decision to the contrary effect.
Subject to the following provisions of this section, any such value shall for the purposes of this section be calculated—
If in consequence of another planning decision or of an order, being a decision or order made—
compensation to which this subsection applies has become or becomes payable in respect of that other planning decision or that order, the calculation to be made under this section shall be made as if that other planning decision had been a decision to the contrary effect, or that order had not been made, as the case may be.
Subsection (3) of this section applies—
In this section " a decision to the contrary effect "—