requirement that the option be ‘exercisable by notice in writing’ was fatal to the invocation of the post rule. The court’s thinking emerged clearly from the following passage from the judgment of Russell LJ: Holwell Securities v Hughes [1974] 1 WLR 155, CA, p 157

Holwell Securities v Hughes [1974] 1 WLR 155, CA, p 157 Russell LJ: It is the law in the first place that prima facie acceptance of an offer must be communicated to the offeror. On this principle, the law has engrafted a doctrine that if, in any given case, the true view is that the parties contemplated that the postal service might be used for the purpose of forwarding an acceptance of the offer, committal of the acceptance in a regular manner to the postal service will be acceptance of the offer so as to constitute a contract, even if the letter goes astray and is lost. Nor, as was once suggested, are such cases limited to cases in which the offer has been made by post. It suffices, I think, at this stage to refer to Henthorn v Fraser. In the present case, as I read a passage in the judgment below, Templeman J concluded that the parties here contemplated that the postal service might be used to communicate acceptances of the offer (by exercise of the option); and I agree with that.