English Contract Law General Principles

“Although the defendant gave the plaintiff six weeks to accept his offer, yet as there was no express stipulation that, for the chance of the plaintiff’s acceptance, the defendant should, during that six weeks, be bound not to retract, the defendant might retract at any time before the plaintiff accepted.”(58)

However, where consideration is provided, the offeror must keep the offer open until…

“…a valid option to purchase constitutes an offer to sell irrevocable during the period stated, and a purported withdrawal of the offer is ineffective. When therefore the offer is accepted by the exercise of the option, a contract for sale and purchase is thereupon constituted, just as if there were then constituted a perfectly ordinary contract for sale and purchase without a prior option agreement.”(60)…