845Commercial rent: comparison with payments other than rentU.K.
(1)Subsection (2) applies—
(a)for the purpose of making a comparison under rule 4 of section 838(3) if section 838 has effect because of section 836(1), and
(b)for the purpose of making a comparison under section 839(3) if section 839 has effect because of section 836(2).
(2)The commercial rent is the rent which might be expected to be paid under a lease, of the land in respect of which the payment mentioned in section 836(1)(b) or (2)(b) is made, which—
(a)was negotiated in the open market when the rentcharge or other transaction mentioned in section 836(1)(b) or (2)(b) was effected,
(b)is a tenant's repairing lease, and
(c)is of an appropriate duration.
(3)A tenant's repairing lease is a lease where the lessee is under an obligation to maintain and repair the whole (or substantially the whole) of the premises comprised in the lease.
(4)To see whether a lease is of an appropriate duration, take the period over which payments are to be made under the rentcharge or other transaction, and—
(a)if that period is 200 years or more (or the obligation to make the payments is perpetual) an appropriate duration is 200 years, or
(b)if that period is less than 200 years, an appropriate duration is the same duration as that period.