258 Sums recoverable from acquiring authorities reckonable for purposes of grant.S
Where—
(a)a sum is recoverable from any authority under section 257 by reference to an acquisition or purchase of an interest in land, and
(b)a grant became or becomes payable to that or some other authority under an enactment in respect of that acquisition or purchase or of a subsequent appropriation of the land,
the power conferred by that enactment to pay the grant shall include, and shall be deemed always to have included, power to pay a grant in respect of that sum as if it had been expenditure incurred by the acquiring authority in connection with the acquisition or purchase.