Where there is a rent review under an existing tenancy, this will operate according to the terms of the lease. Most leases provide for a third party to determine the rent when the landlord and tenant can’t agree. This will usually involve arbitration or independent expert determination. It is advisable to obtain expert professional advice on the determination of the new rent, as this could make a big difference financially. The RICS operate a special scheme for the quick and inexpensive determination of rents at small business premises. If there is to be a new tenancy, and the landlord and tenant cannot agree on the rent, it may be fixed by the court under the Landlord and Tenant Act 1954 Part 2. Again, it would be advisable to obtain professional advice.