When a landlord grants a lease, or makes any other contract fixing the rent of any holding, and, while the lease or contract is in force,--
         (a) land-revenue is for the first time made payable in respect of the holding, or
         (b) land-revenue having been previously payable in respect of it, the revenue payable when the lease or other contract was granted or made is increased or diminished,
     a Revenue-officer may, notwithstanding anything in the record-of-rights or any contract between the parties, by order, on the application of the landlord or of the tenant, alter the rent with reference to the revenue.