11.—In determining for the purposes of section 10 the greatest rent reserved by a lease the following provisions shall have effect:
(a) where during the currency of a lease part of the rent is redeemed by a capital payment, the reduced rent shall be deemed to be the greatest rent reserved by the lease;
(b) a penal rent payable for any breach of covenant and any exceptional rent reserved for a specified period not exceeding five years shall be disregarded.
