20 There are two fundamental problems with accommodating the present facts to these legal concepts. The first is element (2) in Brennan J's list, namely, that the defendant has induced the plaintiff to adopt the relevant assumption or expectation. As the case was put by Mr Murr SC, the relevant assumption or expectation was that a five per cent deposit was payable and no more. The Cutlers themselves did not induce Mr Markson to adopt that assumption or expectation. The way in which it was induced was by the act of their supposed agent, which was unauthorised in that behalf. I do not see how a party can be bound by the act of its unauthorised agent, for the purposes of the second element of Walton Stores v Maher. In this respect the case is distinguishable from Legione v Hateley (1983) 152 CLR 406, in which a party was held bound by the representations of a solicitor's secretary as to the deferral or extension of time for settlement. Gibbs CJ and Murphy J said (at 421-2):
It is of course clear that neither the solicitors, nor Miss Williams, had any actual authority from the vendors to make any representation to the purchasers that the vendors' rights would be kept in abeyance. But the vendors had authorized the solicitors to act for them in completing the sale. Within reasonable limits, the solicitors, having been entrusted by the vendors with the conduct of the negotiations, must be treated as having the authority which, within the course of the negotiations, they purported to exercise: cf Crabb v Arun District Council 53, at p193. "The solicitor is to be regarded as the alter ego of the client and the rights of the other party to the contract cannot be made to depend upon the diligence or lack of diligence exhibited by the solicitor in his dealings with his client": Sargent v ASL Developments Ltd 54, at p659; see also at p649. It was of course the conduct of the vendors that gave the solicitors ostensible authority to act on their behalf. The authority extended to actions carried out in the ordinary course of business by such members or employees of the firm as ordinarily acted for it. When the solicitors selected or permitted Miss Williams to speak on their behalf, in their capacity as solicitors for the vendors, her words bound the vendors. It was no doubt to be expected that if Miss Williams was employed as a secretary, she would promptly communicate the conversation to a member of the firm, who, if he wished to resile from what she had said, could have informed the purchasers' solicitors accordingly. Similarly one would have expected the solicitors to communicate promptly with the vendors - the fact that the vendors were in Queensland does not mean that they were incommunicado - and, again, to inform the purchasers' solicitors of any change of attitude. If there was any lack of diligence on the part of the vendors' solicitors - and we do not suggest that there was - that cannot affect the position of the purchasers.