Viscount Dilhorene (delivering the judgment of the Board):

In 1966 the respondents were engaged in developing sites at Gombak and Ampang for housing. The layout plan for the Gombak housing estate provided for the building of 385 houses and that for the Ampang housing estate of 110 houses. The Gombak site covered 49 acres. Each layout plan made provision for roads giving access to the houses. In March and August 1966 the appellants entered into agreements with the respondents for the purchase of 117 houses on the Gombak estate and 65 houses on the Ampang estate. In the end they bought 143 houses on the Gombak estate. The terms of each agreement were in all material respects the same.

In September 1971 the appellants started proceedings for the recovery of a large sum of money which they alleged they had overpaid for the houses. In their defence and counterclaim the respondents alleged that they were entitled to deduct various sums from the amount which it was alleged they had been overpaid and they counterclaimed for those sums.

The action was settled but it was one of the terms of the settlement that the respondents' counterclaim should be limited to their claim to be entitled to be paid by the appellants the costs incurred by them in relation to the supply of water and electricity to the houses bought by the appellants and to the cost of maintaining roads and drains.

The respondents later abandoned their claim in respect of the maintenance of roads and drains. So the only question to be determined in this litigation is whether the respondents' claim in relation to the supply of water and electricity is well founded. Abdul Hamid J held that it was and his decision was upheld by the Federal Court of Malaysia.

Clause 8 of each agreement reads as follows:

The company further undertakes to apply on behalf of the purchaser for the connection to the said houses of such water and electrical services as are provided by the local authority but all costs of the making of such connections inclusive of the cost of laying water mains and of electric supply and metering thereof shall be borne and paid by the purchaser.

Scheduled to each agreement was a layout plan which showed the plots on which houses were to be erected and the roads on the estate giving access to the houses. Unfortunately these layout plans which, by clauses of the agreements, were to be "taken read and construed as an integral part of" the agreements were not produced at the trial. Layout plans were produced at the trial and, apart from the colour the lots bought by the appellants were painted, their Lordships were told that the plans were the same as those scheduled to the agreements. The layout plans produced showed the position of the water mains on each estate which served the houses bought by the appellants. The layout plan of the Gombak estate produced showed a pump house on what appears to be the north-west corner of the estate with a rising main leading from there and running along a road on the estate to an elevated tank on the north-east corner of the estate and supply mains from the tank running along the road to the appellants' houses and along the road opposite those houses. Save where a supply main passed houses not bought by the appellants on the way to a house or houses they had bought, the layout plan did not show the mains serving the houses not bought. The layout plan of the Ampang estate produced also showed the supply mains serving the houses bought by the appellants on that estate. In the course of the argument, however it emerged that the layout plans scheduled to the agreements did not have marked on them the mains shown on the layout plans produced and consequently, in construing cl. 8 of the agreements, their Lordships ignore the fact that the plans produced at the trial had the mains marked on them.

The issue to be determined was concisely and accurately stated by Suffian LP as whether by virtue of cl. 8 the appellants should "p