Lord Mustill J:

This appeal from a decision of the Court of Appeal of Hong Kong springs from a contract whereby Hoecheong Products Limited ("the sellers") agreed to sell to Cargill Hong Kong Limited ("the buyers") 10,000 tons of cotton seed expellers.The sellers did not deliver the whole contract quantity.The buyers claimed damages.The sellers relied on a "force majeure" clause in the contract to exempt them from liability.The ground asserted was that the contract called for shipment of goods originating in Henan province, and that there had been such a severe drought in Henan during the growing season that it was impossible for them to procure goods from the only permitted suppliers, the China National Native Produce and Animal By- Products Import and Export Corporation ("CNNP"). The buyers denied that the force majeure clause applied to the facts of the case, or that the formalities which it prescribed had been complied with.There were numerous other points of contention between the parties.Although the sum in dispute was, by the standards of modern commercial litigation, comparatively modest, every issue was tenaciously fought.At the trial before Deputy Judge Sharwood the