If at the time the grant is made the landlord’s interest in the dwelling-house is not less than a lease for a term of which more than 125 years and five days are unexpired, the appropriate term is a term of not less than 125 years.

In any other case the appropriate term is a term expiring five days before the term of the landlord’s lease of the dwelling-house (or, as the case may require, five days before the first date on which the term of any lease under which the landlord holds any part of the dwelling-house) is to expire.

If the dwelling-house is a flat contained in a building, which also contains one or more other flats and the landlord has, since 8th August 1980, granted a lease of one or more of them for the appropriate term, the lease of the dwelling-house may be for a term expiring at the end of the term for which the other lease (or one of the other leases) was granted.