77 The fact that the Brides sued as trustees, and not for their personal or beneficial interests, distinguishes this action in some respects from previous cases where they sued on their own behalf. But I consider that the distinction is not entirely conclusive to prevent the operation of the doctrine of issue estoppel. This is because, separating out issues to do with standing and other effects of the Brides' bankruptcies, decisions reached about the existence of default under the securities to ABL, the validity of the appointment of the receivers and managers, the validity of the sales of land by the mortgagee exercising its powers on default, the indefeasibility of the title taken by purchasers at the mortgagees sales and of the title obtained by subsequent transferees do not depend upon whether or not the Brides were suing in their personal capacities or as trustees. This is because the securities granted by them to the bank did not differentiate, in any material respect, between property secured which was held beneficially or held on trust. While the question of the indefeasibility of the titles to land taken by purchasers from the selling mortgagee, or by subsequent transferees depended, in some instances, on the absence of any reasonable basis to contend that the individual purchaser or transferee was implicated in an alleged fraud, and so some of these cases could, on that ground, be differentiated from others, in other instances a finding that ABL, Peat Marwick Mitchell or its partners Young and Anderson were not involved in any fraudulent conduct in relation to those sales where that had been alleged by the Brides would, in my view, give rise to an issue estoppel preventing the Brides from asserting, as against ABL, Peat Marwick Mitchell or subsequent transferees of the land sold at the mortgagees' sales, such as the Fulfords, that the bank, as mortgagee, had engaged in fraudulent conduct in relation to the enforcement of the securities or the sale of the lands. Even if the adjudication of the absence of fraud in such earlier cases dealt with allegations of fraud which, in particular details, were different from the allegations of fraud that the Brides still seek to advance that would not prevent an issue estoppel arising between the same parties or their privies because of the doctrine in Port of Melbourne Authority v Anshun Pty Ltd [1981] HCA 45; (1981) 147 CLR 589.