Proprietary Estoppel in UK Law

The first and fundamental question which must always be resolved is whether, independently of any inference to be drawn from the conduct of the parties in the course of sharing the house as their home and managing their joint affairs, there has at any time prior to acquisition, or exceptionally at some later date, been any agreement, arrangement or understanding reached between them that the property is to be shared beneficially.

Moreover the fundamental principle that equity is concerned to prevent unconscionable conduct permeates all the elements of the doctrine.

One line of authority takes the view that the essential aim of the discretion is to give effect to the claimant's expectation unless it would be disproportionate to do so. The two approaches, in their starkest form, are fundamentally different: see Cobbe v Yeoman's Row Management Ltd [2006] EWCA Civ 1139, [2006] 1 WLR 2964 at [120] (reversed on a different point [2008] UKHL 55; [2008] 1 WLR 1752).

An "estoppel" bars the object of it from asserting some fact or facts, or, sometimes, something that is a mixture of fact and law, that stands in the way of some right claimed by the person entitled to the benefit of the estoppel. The estoppel becomes a "proprietary" estoppel - a sub-species of a "promissory" estoppel - if the right claimed is a proprietary right, usually a right to or over land but, in principle, equally available in relation to chattels or choses in action.

These ingredients should include, in principle, a proprietary claim made by a claimant and an answer to that claim based on some fact, or some point of mixed fact and law, that the person against whom the claim is made can be estopped from asserting. To treat a "proprietary estoppel equity" as requiring neither a proprietary claim by the claimant nor an estoppel against the defendant but simply unconscionable behaviour is, in my respectful opinion, a recipe for confusion.

Applying what Lord Walker said in relation to proprietary estoppel also to constructive trust, that common thread is that, if the parties intend to make a formal agreement setting out the terms on which one or more of the parties is to acquire an interest in property, or, if further terms for that acquisition remain to be agreed between them so that the interest in property is not clearly identified, or if the parties did not expect their agreement to be immediately binding, neither party can rely on constructive trust as a means of enforcing their original agreement.

Nevertheless most scholars agree that the doctrine is based on three main elements, although they express them in slightly different terms: a representation or assurance made to the claimant; reliance on it by the claimant; and detriment to the claimant in consequence of his (reasonable) reliance (see Megarry & Wade, Law of Real Property, 7th edition (2008) para 16-001; Gray & Gray, Elements of Land Law, 5th edition (2009) para 9.2.8; Snell's Equity, 31st edition (2005) paras 10-16 to 10-19; Gardner, An Introduction to Land Law (2007) para 7.1.1).