Despite the lack of a definitive formulation, it is widely accepted that the elements of assurance, reliance and detriment must be present in order to found a claim of proprietary estoppel. The doctrine has however been widely criticised for being too flexible and uncertain. The main cause of this uncertainty is the lack of clarity surrounding the role of unconscionability. It has been stated that unconscionability is “at the heart of the doctrine,” and yet there is “little guidance as to what it means, little explanation of why it is at the centre and thus virtually no consideration of the role it might play in providing both a justification for, and a limitation on, successful estoppels”