Proprietary estoppel

Proprietary estoppel prevents a landowner from unconscionably resiling from an assurance on which another has detrimentally relied. The doctrine requires three interconnected elements: (i) an assurance or representation by the landowner; (ii) reliance by the claimant on that assurance; and (iii) detriment suffered as a consequence, such that it would be unconscionable for the landowner to go back. As established in Gillett v Holt, these elements are not rigid silos but facets of a broad inquiry into unconscionability, assessed 'in the round'. The doctrine operates as an exception to statutory formality requirements (LPA 1925 s 2, s 53(1)(c)) and provides flexible remedial responses ranging from monetary compensation to transfer of the fee simple. The overarching principle is preventing unconscionable conduct—a context-sensitive standard that gives the doctrine both its flexibility and its uncertainty.

Gillett v Holt [2001] Ch 210: Claimant worked unpaid for 40 years relying on assurances of inheriting the farm; established that the tripartite test must be viewed holistically through the lens of unconscionability. Fundamental for rejecting mechanical application of elements and emphasising remedial flexibility.

Thorner v Major [2009] UKHL 18: Oblique statements over 30 years sufficed for assurance in farming context; the test is whether assurance was 'clear enough' in context. Crucial for showing assurance need not be contractually certain and context is decisive.

Jennings v Rice [2002] EWCA Civ 159: Court awarded £200,000, well below the house and furniture she expected (~£435,000, from a ~£1.285m net estate), despite 'all this will be yours' assurance; established 'minimum equity to do justice' principle. Central authority on remedial proportionality between expectation and detriment.

Greasley v Cooke [1980] 1 WLR 1306: Once assurance and conduct shown, reliance is presumed and burden shifts to defendant to disprove it. Essential evidential principle simplifying claimant's burden.

Guest v Guest [2022] UKSC 27: Supreme Court emphasised detriment must be substantial and unconscionability requires rigorous foundation. Signals judicial caution and tightening of requirements.

Courts first examine whether an assurance exists—express or implied, viewing words/conduct objectively in context. Silence plus knowledge of mistaken belief may suffice where claimant incurs expenditure. Once assurance and subsequent conduct established, reliance is presumed (Greasley v Cooke). Detriment is construed broadly: expenditure, improvements, personal services, forgone opportunities, life changes. The court then assesses unconscionability holistically. If equity established, remedy follows 'minimum equity to do justice' principle: courts balance expectation, detriment, proportionality, clarity of assurance, and practical considerations. Full expectation may be awarded where assurance clear and reliance substantial (Thorner), but proportionate monetary awards common where expectation disproportionate to detriment (Jennings). The doctrine circumvents formalities as it arises by operation of law and falls within LPA 1989 s 2(5) exception for constructive trusts (Yaxley v Gotts).

Conflating proprietary estoppel with common intention constructive trusts—while overlapping, estoppel requires assurance/reliance/detriment whereas constructive trust needs common intention plus detrimental reliance. Applying tripartite test mechanically without engaging unconscionability—Gillett requires holistic assessment. Ignoring remedial stage—always discuss what remedy likely and why (expectation vs detriment, proportionality). Confusing with promissory estoppel which is defensive only and cannot found claims. Missing evidential presumption of reliance from Greasley v Cooke. Treating 'minimum equity' as meaning modest remedy—it means 'no more than necessary' which may be entire farm (Thorner).