Lord Diplock :

(delivering the judgment of the Board): In 1931 an agreement relating to tin mining rights in Perak was made between three parties. It is convenient to refer to these parties and their respective successors in title as "the company", the "sub-lessees" and the "sub-sub-lessee". The company held mining leases from the State of Perak over four parcels of land. These the company had sub-let to the sub-lessees. The company was dissatisfied with the manner in which the sub-lessees were complying with their obligations to work the mines under the sub-leases and the contract provided that the sub-lessees should grant sub-sub-leases of these parcels to the sub-sub-lessee who was already mining adjacent parcels of land. The contract further provided that the sub-sub- lessee should mine the parcels of which the company was lessee together with the parcels already being mined by the sub-sub-lessee as a single mine under a comprehensive mining scheme. Clause 4 of this contract contemplated the acquisition by the company of mining leases over other parcels of land in the vicinity of those which formed part of the comprehensive mining scheme.

Many years later the company