(a) Smith v. Hughes, ubi sup.

(b) See Webster v. Cecil, 30 Beav. 62, as explained in Tamplin v. James, 15 Ch. D. 215, 221; Paget v. Marshall, 28 Ch. D. 255, 265. The case appears to be governed by the same principle as is applied in holding that a man is not bound by the exact terms of a description or representation which he has put forward or made to another, where the other has notice that its terms are inaccurate; above, pp. 541, 686 and n. (j); Calverley v. Williams, 1 Ves. jun. 210; Townshend v. Stangroom, 6 Ves. 328, 341.

So far, in discussing the subject of mistake as excluding any true consent between the parties, and so avoiding the contract altogether, we have dealt mainly with the rules of the common law(d). Where the contract is void on this ground, the parties are in the same position in equity as at law. There can be no question of any order for specific performance of the contract, for this remedy is, as we have seen (e), only granted to enforce a valid contract. But where one party has entered into the contract under a mistake, which is not shared by the other, and the one is estopped at law from setting up his mistake and proving his true intention, the parties are not always in the same position, as regards the equitable remedies to enforce the contract, as they are at law. Thus where the vendor makes a mistake in the preparation of the particulars of sale, and includes therein more than he really meant to sell (f), but the description is precise, so that a man would naturally and reasonably suppose that the vendor meant to sell what he actually offered, the contract is enforceable against the vendor at law, since he would be estopped from proving his mistake (g).

Mistake as avoiding true consent in equity.

Unilateral mistake in equity.

(c) See Garrard v. Frankel, 30 Beav. 445; Harris v. Pepperell, L. R. 5 Eq. 1; Bloomer v. Spittle, L. R. 13 Eq. 427; Paget v. Marshall, 28 Ch. D. 255; as explained in May v. Platt, 1900, 2 Ch. 616, 623; Pollock on Contract, 495, 7th ed. ; below, pp. 710 sq.

(d) Above, pp. 667 sq.

{e) Above, p. 678.

(/) See Re Fawcett and Holmes, 42 Ch. D. 150; above, p. 640; May v. Platt, 1900, 1 Ch. 616.

(g) Above,pp. 668,670,673,676.

The vendor is also estopped from setting up his mistake in equity to this extent, that he is not entitled to claim the rescission of the contract (h), or to insist himself on its specific performance, except on the terms of conveying the whole of the property described, if he be able to do so (i). If he be not, he may, as we have seen (k), enforce specific performance with an abatement of the purchase money, where the deficiency is insubstantial or the contract contained an express stipulation as to compensation for misdescription. But if the purchaser sue for specific performance of the contract, then the vendor may in certain circumstances be entitled to set up his mistake as a defence to the action. This is owing to the discretionary nature of the remedy of specific performance, and to the fact that in granting or withholding such relief the Court will have regard to circumstances outside the contract and especially to the conduct of the parties, and may refuse specific performance on the ground of great hardship (/). But it is not in every case that a party sued for specific performance may avail himself of his own mistake as a defence to the action. If the mistake were entirely due to the defendant's own carelessness or inadvertence, the plaintiff having done nothing to induce or contribute to the error, nor having sought knowingly to take advantage of it, and if it will inflict no great hardship on the defendant to enforce him to perform the contract specifically, then it appears that the defendant will be equally precluded from resisting specific performance in equity as from avoiding his liability at law (m). Thus where the vendor has in these circumstances inadvertently included in the particulars of sale more than he meant to sell, he will nevertheless be obliged at the purchaser's suit to perform the contract specifically, and must convey the whole property described, if he can; or if he cannot, he must convey what he can with a proportionate abatement of the price (n). So it appears that, in the like circumstances, a purchaser who has by his own mistake signed a contract to buy a property smaller than he supposed it was (o), or even different from that which he intended to buy (p), cannot resist specific performance on the ground of his mistake. But where it would be a great hardship on the party mistaken to oblige him to perform the contract specifically, the Court will not grant this relief to the other party, but will leave him to pursue his remedy at law (q). Thus where one wrote a letter offering by mistake to sell his land for 1,250l., meaning to say 2,250l., and the offer was accepted, the Court refused to grant specific performance at the purchaser's suit (r). And where a vendor has by his own mistake included in the particulars of sale much more than he meant to sell, it appears that the Court may decline, on the ground of hardship, to order the specific performance of the contract at the purchaser's suit, unless he elect to take, without compensation, what the vendor really intended to sell (s). So also we have seen that where a vendor has innocently made a serious error of description to his own disadvantage, and has so purported to sell a much larger property than he has, the purchaser will not be entitled to enforce specific performance with compensation, if this would be a great hardship on the vendor (t). And where one party has contributed in any way to the other's mistake, as if the particulars of or contract for sale contain any misrepresentation or any ambiguity likely to mislead a man of ordinary intelligence using ordinary care, then the other party may resist the specific performance of the contract on the ground of his mistake (u). If the description of the land sold in the written agreement erroneously comprise more than the vendor means to sell, but the purchaser have notice, before or at the time of sale, what land the vendor really intends to part with, the purchaser cannot enforce the specific performance of the contract according to the written description; for the vendor may in defence prove by evidence outside the written agreement that it does not express the parties' true intention (as). And as we have seen (y), if in such case the vendor have no title to the land erroneously comprised in the contract, the purchaser is not entitled to claim specific performance with compensation. If one party were aware of the other's mistake and wrongfully took advantage of it, he cannot enforce the specific performance of the contract against the party mistaken (z). Indeed in this case, as we have seen (a), it may be contended that the contract is void at law.