ABSTRACT
Proprietary estoppel can provide a defence to an action by a landowner who seeks to enforce his strict rights against someone who has been informally promised some right or liberty over the land. The conditions for the operation of proprietary estoppel were fairly strictly drawn and these were codified by Fry J in Willmott v. Barber. Proprietary estoppel cannot be established unless the claimant can prove that he has suffered some detriment in reliance on the assurance. It is clear that Oliver J in Taylor Fashions regarded unconscionability as the very essence of a claim of proprietary estoppel. Equally clear is the point made by the Court of Appeal when upholding the estoppel claims in Gillett and Jennings: assurance, reliance and detriment are necessarily interwoven and the court should not approach them forensically as if they were entirely separate requirements.
