Template:Estoppel quote Kosmar

Estoppel, however, is a promise, supported not by consideration but by reliance. It is a promise not to rely upon a defence (per Lord Diplock) or a right (per Lord Goff). It requires a representation, in words or conduct, which must be unequivocal and must have been relied upon in circumstances where it would be inequitable for the promise to be withdrawn. The need for such unfairness probably means that the reliance of the representee has to constitute a detriment, but even the detriment has, I would think, to be such as to make it inequitable for the promise to be withdrawn. For these reasons, the estoppel may not be irrevocable, but may be suspensory only. An unequivocal representation without the necessary reliance, and reliance without the necessary unequivocal representation, are each insufficient.