Where an allowable loss accrues to a person on a disposal of an interest in land to which the principal section applies, being a disposal in relation to which paragraph 23 of Schedule 6 to the Finance Act 1965 (sales of land in United Kingdom reflecting development value) applies, then, if the amount of the loss is by virtue of sub-paragraph (4) of that paragraph computed without regard to Part II of that Schedule (assets held on 6th April 1965), this Chapter shall have effect in relation to that disposal as if in subsection (4) of the principal section and paragraphs 11 and 12 of Schedule 3 to this Act (as applied by paragraph 5 of this Schedule) any reference to the current use value of the interest at the time of its acquisition by the person making the disposal or, if the interest was acquired by him before 6th April 1965, its current use value at that date referred only to its current use value at the time of its acquisition by him.