Lord Denning, M.R., in D & C Builders Ltd. v. Rees (1965) 3 All ER 837 at 840: “In point of law, payment of a lesser sum, whether by cash or cheque, is no discharge of a greater sum. This doctrine of the common law has come under heavy fire. It was ridiculed by Sir George Jessel, MR., in Couldery v. Bartrum (1881) 19 Ch. D. 394 at p. 399. It was held to be mistaken by Lord Blackburn in Foakes v. Beer (1884) 9 App. Cas at p. 622. It was condemned by the Law Revision Committee in their Sixth Interim Report (Cmnd 5449) paragraph 20 and 22. But a remedy has been found. Equity has stretched out a merciful hand to help the debtor. The courts have invoked the broad principle stated by Lord Cairns L.C., in Hughes v. Metropolitan Railway Co. (1877) 2 App. Cas 439 at p. 448: ‘…….it is the first principle upon which all courts of equity proceed if parties, who have entered into definite and distinct terms involving certain legal results………afterwards by their own act, or with their own consent, enter upon a course of negotiation which has the effect of leading one of the parties to suppose that the strict rights arising under the contract will not be enforced, or will be kept in suspense, or held in abeyance, that the person who otherwise might have enforced those rights will not be allowed to enforce them where it would be inequitable, having regard to the dealings which have taken place between the parties.’ It is worth noting that the principle may be applied, not only so as to suspend strict legal rights, but also so as to preclude the enforcement of them. This principle has been applied to cases where a creditor agrees to accept a lesser sum in discharge of a greater. So much so that we can now say that, when a creditor and a debtor enter on a course of negotiation, which leads the debtor to suppose that, on payment of the lesser sum, the creditor will not enforce payment of the balance, and on the faith thereof the debtor pays the lesser sum and the creditor accepts it as satisfaction; then the creditor will not be allowed to enforce payment of the balance when it would be inequitable to do so. In applying this principle, however, we must note the qualification. The creditor is barred from his legal rights only when it would be inequitable for him to insist on them. Where there has been a true accord, under which the creditor voluntarily agrees to accept a lesser sum in satisfaction, and the debtor acts on that accord by paying the lesser sum and the creditor accepts it, then is is inequitable for the creditor afterwards to insist on the balance.”
