s 364 General rule as to what is the relevant interest
(1) The relevant interest in relation to any qualifying expenditure is the freehold or leasehold interest in the related agricultural land to which the person who incurred the expenditure on the construction of the agricultural building was entitled when the expenditure was incurred. (2) Subsection (1) is subject to the following provisions of this Chapter. (3) If, when the expenditure was incurred— (a) the person was entitled to freehold and leasehold interests or to more than one leasehold interest in the related agricultural land, and (b) one of those interests was reversionary on all the others, the reversionary interest is the relevant interest.