If any question arises whether the withholding of a consent required by virtue of section 81 above was unreasonable it is for the landlord to show that it was not; and in determining that question the court shall, in particular, have regard to the extent to which the improvement would be likely—
to make the dwelling-house, or any other premises, less safe for occupiers;
to cause the landlord to incur the expenditure which it would be unlikely to incur if the improvement were not made; or
to reduce the price which the dwelling-house would fetch if sold on the open market or the rent which the landlord would be able to charge on letting the dwelling-house.
A consent required by virtue of section 81 may be validly given notwithstanding that it follows, instead of preceding, the action requiring it and may be given subject to a condition.
Where the tenant has applied in writing for a consent which is required by virtue of section 81 then—
if the landlord refuses to give the consent it shall give to the tenant a written statement of the reasons why the consent was refused; and
if the landlord neither gives nor refuses to give the consent within a reasonable time, the consent shall be taken to have been withheld, and if the landlord gives the consent but subject to an unreasonable condition, the consent shall be taken to have been unreasonably withheld.
If any question arises whether a condition attached to a consent was reasonable, it is for the landlord to show that it was.