Lord Diplock J:

(delivering judgment of the Board):This appeal from the Federal Court of Malaysia is about the right to mine tin in an area of land near Papan Town in the State of Perak, and, in particular, in what was formerly part of the Railway Reserve for the Ipoh-Tronoh line.It turns upon the meaning of a forty-year-old agreement dated 22 October 1931.To this agreement there were three parties described as "the company", "the sub-lessee" and "the miner". The company is the appellant in this appeal, the interest of the sub-lessee in the agreement has devolved upon the second respondent and the interest of the miner is represented in this appeal by the first respondent as a consequence of events which it is no longer necessary to canvass in order to dispose of the appeal.Their Lordships will adopt the expressions "the company", the "sub-lessee" and "the miner", as referring also to those persons by whom the corresponding interest of the original party to the agreement was from time to time represented.

At all material times mining lands in Perak have been vested in the Sultan and the working of minerals regulated by the Mining Enactment.This provided for the grant of mining leases which imposed upon the lessee an obligation to carry on mining operations upon the land subject to the lease and for that purpose to employ at work on that land a specified number of labourers or equivalent labour-saving apparatus.It authorised the grant by the lessee of sub-leases and by sub-lessees of sub-subleases but only upon the terms prescribed by the Enactment.These terms provided that the sub-lessee or sub-sublessee should work the minerals in accordance with the terms of the head-lease and should pay tribute to the sub-lessor at an agreed rate calculated on the total amount of ore removed from the land.Section 20 of the Mining Enactment enabled permission to be granted on behalf of the Government to any person holding lands under more than one title whether as lessee, sub-lessee or sub-sub- lessee to treat the aggregate area of his holding as a single mine and to set to work upon any part of that area where they could be used to best advantage, the total number of labourers or equivalent labour-saving apparatus which, but for such permission, he would have been required under each separate head-lease to be kept at work on the particular area subject to that lease.

In 1931 the company was engaged in the business of prospecting for tin.It did not undertake actual mining operations.It acquired head-leases of mining lands which it had prospected and entered into subleases (in the form provided in the Mining Enactment) with persons who undertook the actual mining operations.

In the early part of 1931 there were 14 plots of mining land near Papan Town held under separate head-leases.The company was head-lessee of numbers one to four.It had sub-let them to the sub- lessee who was mining them himself.Head-leases of the plots numbered five to 14 were held, as to one by the company, five by the sub-lessee and four by various third parties.These ten plots were sub-let to the miner, who was mining them.All fourteen plots were adjacent to one another except that across them from east to west there ran the Railway Reserve, a strip of about 18 acres in extent, which was not available for mining.The eastern part of this strip lay between the company's plot two on the north and plot three on the south; the western part lay between plots six and seven on the north and plot five on the south.

The company was dissatisfied with the way in which the sub-lessee was mining plots one to four.Agreement was reached between the company, the sub-lessee and the miner that all fourteen plots should in future be worked by the miner as one mine known as the Khong Heng Kongsi Mine, under a comprehensive mining scheme described as the "Kacha and Menelai Comprehensive Mining Scheme" for which permission was to be sought from Government under s. 20 of the Mining Enac