In this Division--
(a) a reference to an option contained in a lease is a reference to a right on the part of the lessee to require the lessor--(i) to sell, or offer to sell, to the lessee the reversion expectant on the lease, or(ii) to grant, or offer to grant, to the lessee a renewal or extension of the lease, or a further lease, of the demised premises or a part thereof,whether the right is conferred by the lease or by an agreement collateral to the lease, and
(b) a reference to a breach by a lessee of the lessee's obligations under a lease containing an option is a reference to a breach of those obligations by an act done or omitted to be done before or after the commencement of the Conveyancing (Amendment) Act 1972 , in so far as the act or omission would constitute a breach of those obligations if there were no option contained in the lease.