Once upon a time the rules for deciding when an acceptance of an offer took effect were clear.

(1) First the method of communication used to transmit the acceptance had to be classified as instantaneous or non-instantaneous.

(2) If it was instantaneous, the acceptance only became effective on arrival. If it did not arrive, there was no contract. See Entores Ltd. v. Miles Far East Corporation [1955] 2 Q.B. 327. This rule was applied where the parties or their agents were face to face or were communicating by telephone or telex.

(3) In Entores, Denning, L.J. (as he then was) qualified r. 2. His Lordship said that if a message failed to arrive through the fault of the offeror, he would be estopped from denying that he received it. Since this estoppel was only a defence and could not be used by the offeror against the offeree, the effect would be that the offeree had the choice of whether or not to hold the offeror to the “contract”. This qualification has not been applied in any reported case.

(4) If the method of communication was non-instantaneous, it was eventually settled that the acceptance took effect on dispatch. This rule was applied to communications by letter and by telegram. It was irrelevant that the communication failed to arrive. See Household Fire and Carriage Accident Insurance Co. Ltd. v. Grant (1879) 4 Ex. D. 216.

(5) Rule 4 only applied “where the circumstances are such that it must have been within the contemplation of the parties that, according to the ordinary usages of mankind, the post might be used as a means of communicating the acceptance”. See Henthorn v. Fraser [1892] 2 Ch. 27, per Lord Herschell.

(6) It was, therefore, always open to the offeror as the person who (in theory) had control to vary these rules. So, he could waive the need for any communication: Carlill v. Carbolic Smoke Ball Co. [1893] 1 Q.B. 256. Or he could stipulate that an acceptance sent by letter had to arrive: Holwell Securities Ltd. v. Hughes [1974] 1 All E.R. 161.

Professor Treitel has always stood out by insisting that there is no general rule that acceptance sent by a non-instantaneous means of communication takes effect on dispatch. His view has been that posting a letter of acceptance, for example, is merely an act of greater contractual significance that certain other acts, namely, subsequent withdrawal of the offer, loss or delay of the acceptance and subsequent sale of subject matter involved. See Law of Contract (5th edn.) pp. 20–21 and Doctrine and Discretion in the Law of Contract (1981), p. 9.