“Mr. Gibbon did not merely execute the deed under a mistake of law as to the legal consequences of his doing so. He executed it under a mistake as to its legal effect … Since its effect was not that which he intended, he is entitled to have it set aside.”
“If anything, it is simply a formula designed to ensure that the policy involved in equitable relief is effectuated to keep it within reasonable bounds and to ensure that it is not used simply when parties are mistaken about the commercial effects of their transactions or have second thoughts about them.”
“It is plain in my judgment that a mistake of fact is capable of bringing the equitable jurisdiction into play. All that is required is a mistake of a sufficiently serious nature. In my judgment a mistake about an existing or pre-existing fact if sufficiently serious is enough to bring the jurisdiction into play. If and to the extent that Millett J intended to restrict the scope of the equitable jurisdiction to a mistake about the effect of a transaction, I respectfully disagree.”