Can a unilateral offer of an option without consideration be revoked?

The agreement in question here (ex. P. 2, supra) differs from an option agreement in a few important respects. First of all, one readily sees that it is signed by the two vendors and the purchaser under seal. Then again in Davidson v. Norstrant, supra, Idington, J., at pp. 384-5 said: I agree that a unilateral offer of an option without consideration can be revoked at any time, unless under seal as this contract was. I am of the opinion that if the offer is made under seal and not accepted it may be withdrawn within a reasonable time and that the measure of such time might under certain circumstances be very brief indeed. I am further of opinion that if there is no other consideration than mutual promises, an agreement for an option without seal, may be enforceable. Such promissory consideration may be in shape of a promissory note, or a promise to give one, or something else of value. And when the contract for an option, as here, is under seal and purports to bind for a specific time, assented to by the covenantee, it binds without the payment of any consideration. And the binding effect thereof cannot be affected by any mere omission to pay what is named as the consideration which has been declared to have been received, unless and until the offeror has demanded from him bound to pay such consideration, and been refused. . . . . . The man contracting under seal to give an option to the other party thereto, and stipulating for a consideration named, is entitled to have it paid, but even if it is not paid, it stands as a debt due and, by oral evidence, can be so shewn despite the acknowledgment of its receipt. That debt, or price of consideration, remaining due and owing by virtue of the bargain attested by such debtor executing the contract, is sufficient consideration even if he owing it never accepts the option.