(1)Where an agreement in writing secures to the tenant of an agricultural holding, for an improvement for which compensation is payable by virtue of section 79 or section 80 above, fair and reasonable compensation having regard to the circumstances existing when the agreement was made, the compensation so secured shall, as respects that improvement, be substituted for compensation under this Act.
(2)The landlord and tenant of an agricultural holding who have agreed that the holding shall be let or treated as a market garden may by agreement in writing substitute, for the provisions as to compensation which would otherwise be applicable to the holding, the provisions as to compensation known as the " Evesham custom ", and set out in subsections (3) to (5) of section 80 above.