Under what circumstances will a party be permitted to enter into an agreement for sale without the consent of the other party?

The Appellants rely principally on the decision of Mr. Justice Middleton in Clergue v. Plummer (1916), Vol. 37, O.L.R. 432. In this case a purchaser sought specific performance of an Agreement for Sale against the estate of a deceased vendor. It was contended on behalf of the estate that the Agreement had been to sell an undivided one-half interest in the lands in question. After the vendor's death, the executors found among his papers a document signed by him which, but for the last clause, was substantially a copy of a document delivered to the plaintiff. There was added, however, these words: "I further agree to assign the aforesaid one undivided one-half interest to you or your assigns whenever you demand the same, or if you prefer to leave title in me I will give you a declaration of trust that I hold such one-half interest for you." Mr. Justice Middleton reviewed a number of the authorities and made this atatement, on which this Appellant relies: "In the great majority of cases, the question discussed has been the effect of an entry of a receipt of money made by the recipient. At the time the entry was made, it was, no doubt, against the interest of the recipient; and it was therefore unlikely that he would record the receipt of money which would either discharge an existing debt due to him or create a liability to account on his part, unless the money was actually received. At the time of the entry, its sole effect would therefore be against the interests of the person making the entry. At the time of the trial, the effect of the entry might be favourable to the case of the party making it -- e.g., it might have the effect of taking a debt, otherwise statute-barred, out of the statute. Nevertheless, had it been originally against interest, it was admitted. But it was also held tht the entry must be admitted in its entirety; and therefore, where a part of the entry was against the interests of the person making it, and another part of the entry was not against but in favour of his interest, in this way self-serving entries became admissible; and, as I understand the cases, this has never been departed from, it being a matter in each case for judicial discrimination as to the weight to be attached to the evidence."