The rent review was to 'such rents as shall have been agreed between the Lessor and the Lessee' without any detailed valuation formula and with no machinery for determining the new rent if the parties failed to agree. Since the parties had clearly agreed to have a review clause (and the omission of a proper clause was a mistake by the landlord's solicitors which the tenant's solicitors had noticed but had not pointed out) the lease was to be rectified to add an arbitration provision and it was also to be implied that the new rent was to be that which it would be reasonable for the parties to have agreed in the light of all considerations that would affect the parties' minds in negotiation.
