Grievson v Grievson [2011] EWHC 1367 (Ch), [2011] All ER (D) 58 (Jun)
When it came to estoppel by representation or promissory estoppel, it was unlikely that a claimant would be able to satisfy the test of unconscionability unless he could also satisfy the three classic requirements. They were: (a) a clear representation made by the defendant upon which it was reasonably foreseeable that the claimant would act; (b) an act on the part of the claimant which was reasonably taken in reliance upon the representation or promise; and (c) after the act had been taken, the claimant being able to show that he would suffer detriment if the defendant was not held to the representation or promise.
With regard to estoppel by convention, the principles applicable were, inter alia, that it was not enough that the common assumption upon which the estoppel was based was merely understood by the parties in the same way. It had to be expressly shared between them, and the expression of the common assumption by the party alleged to be estopped had to
