46. While the valuation is to be undertaken by the appellant itself, the respondent does not suggest that this renders cl 14.2(b)(iv) void for uncertainty. In any event, such a submission would be untenable. Any uncertainty would be cured by the implication of terms requiring the appellant to value by reference to objective criteria. The appellant accepts that those criteria are that it should act honestly, bona fide, and reasonably. The respondent does not dispute that terms to this effect should be implied in the contract. In my view, it is indeed implicit in the contract that, in carrying out a valuation in terms of cl 14.2(b)(iv), the appellant is obliged to act honestly, bona fide, and reasonably: see Sandhu v Ferizis, unreported; SCt of NSW (Young J); 4630 of 1990; 11 March 1994, and cases such as Perini Corporation v Commonwealth [1969] 2 NSWR 530. It was not suggested by the respondent that the appellant should act with due care and skill in performing the valuation. Ordinarily, when a third party carries out such a valuation, the value determined cannot be challenged because of negligence on the part of the valuer: Legal and General Life of Australia Ltd v A Hudson Pty Ltd (at 335). That rule may not apply when the valuer is not a third party but a party to the contract itself. As there was no argument on the question, I express no concluded opinion as to it. I merely observe that the mere fact that a party to a contract is appointed as a valuer of a thing, which is to pass as consideration under the contract, does not mean that that party is at large to determine any value it wishes. Conditions will be implied in the contract which will govern the performance of the valuation function. For the purposes of this appeal, having regard to the way in which the matter was argued, I shall assume that those conditions are solely that the appellant is obliged to act honestly, bona fide, and reasonably.