This rule can be illustrated in an example where A makes an offer by post to sell land to B. The next day, A decides to revoke the offer and thus A puts a letter in the post to B revoking the offer. Before the revocation proposal reaches B, B has sent A a letter accepting the offer. The revocation letter sent by A reaches B only after the acceptance letter is sent. In this example, A cannot revoke the offer because B has already accepted the offer. A contract exists when the letter of acceptance is sent, regardless of whether the letter comes to the attention of A, the