contracting. It appears that for this principle to operate, the course of dealings needs to be long, continuous and consistent. It also seems implicit in the cases that it is considerably easier to advance this argument in a commercial context rather than a consumer one (where it is far less reasonable to assume that information in the small print would put someone on guard).

It was indicated at the beginning of this chapter that (whatever the precise meaning of contract) the common law adopts a broadly objective test as to contract formation. It follows from this that merely because one party mistakenly believes some fact of the contract (for example, the precise nature of the subject matter) to be other than it is, this will not invalidate the existence of a contract, unless (at the very least) this mistake was so obvious as to be objectively apparent. A classic illustration of this is the well known case of Smith v Hughes,89 which concerned the sale of oats believed by the buyer to be old – but which the seller knew to be new. Cockburn LJ sums up the general judicial approach:

Smith v Hughes (1871) LR 6 QB 597, p 606 Cockburn LJ: It only remains to deal with an argument which was pressed upon us, that the defendant in the present case intended to buy old oats and the plaintiff to sell new, so the two minds were not ad idem; and that, consequently, there was no contract. This argument proceeds on the fallacy of confounding what was merely a motive operating on the buyer to induce him to buy with one of the essential conditions of the contract. Both parties were agreed as to the sale and purchase of this particular parcel of oats. The defendant believed the oats to be old, and was thus induced to agree to buy them, but he omitted to make their age a condition of the contract. All that can be said is that the two minds were not ad idem as to the age of the oats; they certainly were ad idem as to the sale and purchase of them. Suppose a person were to buy a horse without a warranty, believing him to be sound, and the horse turns out unsound, could it be contended that it would be open to him to say that, as he had intended to buy a sound horse and the seller to sell an

unsound one, the contract was void, because the seller must have known from the price the buyer was willing to give, or from his general habits as a buyer of horses, that he thought the horse was sound? The cases are exactly parallel.