(1) In this section -
"inferior interest" means any interest in or right over the building or structure in question, whether granted by the relevant person or by someone else;
"premium" includes any capital consideration except so much of any sum as corresponds to any amount of rent or profits which is to be computed by reference to that sum under section 98;
"capital consideration" means consideration which consists of a capital sum or would be a capital sum if it had taken the form of a money payment;
"rent" includes any consideration which is not capital consideration;
"commercial rent" means such rent as might reasonably be expected to have been required in respect of the inferior interest in question, having regard to any premium payable for the grant of the interest, if the transaction had been at arm's length.
(2) This section shall apply where -
(a) the relevant interest in a building is sold subject to an inferior interest,
(b) by virtue of the sale a balancing allowance under
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