Dickinson v Dodds
(1876) 2 Ch D 46
On 10 June Dodds offered to sell house to Dickinson, stating ‘this offer to remain open until 9.00am on 12 June". Dickinson decided to accept on 11 June but did not advise Dodds immediately. Later on the 11th Dickinson was informed by a third party that Dodds had sold to someone else. Dickinson then purported to accept the offer. Dodds replied that it was too late - the property had already been sold.
No particular form of revocation is required. All that is required is that the offeror in some way conveys (directly or indirectly) to the offeree that s/he had changed his or her mind about the offer. There was no question that this had occurred here - Dickinson knew Dodds was no longer prepared to sell before purporting to accept. The promise to keep the offer open was not binding because it was not supported by consideration.