ChD, 31 July 1986. Tenants sought a declaration as to the meaning of a rent review clause in an underlease. The clause provided that the full yearly market rent meant the rent at which the property might reasonably be expected to be let in the open market. The tenants submitted that there should be no assumption that there would be a willing lessee. The landlords submitted that the formula must be applied on the assumption that there would be a letting, whatever might be the result of testing the appropriate open market. ChD held, rejecting the landlord's submission, that there was no justification for incorporating a wholly unreal factor into a hypothetical exercise which the review clause demanded. If examination of the appropriate open market showed no willing lessee at any price the formula should not be construed as requiring a willing lessee to be invented. Declaration to be agreed by the parties in the light of the judgment.