2If the person entitled to the compensation under the said section 31—
(a)was, at the time of the compulsory acquisition or sale mentioned in subsection (1) of that section, entitled to an interest in land held with the land acquired or purchased ; but
(b)is, at the time of the planning decision in question, no longer entitled to that interest, either in respect of the whole or in respect of part of that land ;
any reference in the said section 31 to the principal amount of any compensation or the amount of the purchase price shall be construed as excluding so much of the compensation or purchase price as was or would have been attributable to severance or injurious affection of that land or, as the case may be, of that part.