(1) This section applies where:
(a) an interest in land is acquired from a person by compulsory process;
(b) immediately before the acquisition, a planning instrument was in force having the effect of limiting or restricting the permissible use of the land to use for a purpose of a public nature;
(c) the planning instrument was made to meet the needs of an acquiring authority; and
(d) the planning instrument was not in force in relation to the land at the time the person acquired the interest.
(2) In determining the amount of compensation to which the person is entitled in respect of the acquisition of the interest:
(a) the limitation or restriction on the use of the land imposed by the planning instrument shall be disregarded;
(b) it shall be assumed that the land was subject only to such limitations and restrictions as would have been likely if there had been no proposal to limit or restrict the use of the land to use for the purpose permitted by the planning instrument; and
(c) the amount of any compensation paid or payable to the person in consequence of the planning instrument shall be deducted from the compensation to which the person would otherwise be entitled.