Every power conferred by custom or contained in a statute (except as hereinafter mentioned) or other instrument authorising a tenant for life of full age, statutory owner, trustee, or other person to grant a lease or underlease with a covenant or obligation for perpetual renewal, shall have effect, in regard to any grant made after the commencement of this Act, as if the same authorised the grant of a lease or underlease for a term not exceeding two thousand years at the best rent that can be reasonably obtained, having regard to any fine which may be taken and to all the circumstances of the case, or, if the power authorises a grant at a peppercorn rent or other rent less than the best rent, then at any rent so authorised.

Every power to grant a lease or underlease at a rent or in consideration of a fine for life or lives, or for any term of years determinable with life or lives or on the marriage of any person, shall have effect in regard to any grant made after the commencement of this Act, as if the same authorised the grant of a lease or underlease for a term not exceeding ninety years determinable after the death or marriage (as the case may be) of the original lessee or of the survivor of the original lessees by at least one month’s notice in writing given to determine the same on one of the usual quarter days, either by the lessor or the persons deriving title under him to the person entitled to the leasehold interest, or by the lessee or other persons in whom the leasehold interest is vested to the lessor or the persons deriving title under him.