The Concept of Proprietary Estoppel in relation to Contentious Probate

Proprietary estoppel is an equitable doctrine that can give someone a right over property they were promised but never formally given. In contentious probate it matters enormously: it is the main route by which a person promised an inheritance during the deceased’s lifetime can claim it when the will says otherwise. This guide explains the elements, the leading cases and what the courts actually award. It applies to England and Wales.

What is proprietary estoppel?

Proprietary estoppel provides a remedy where one person has been led to believe they will acquire an interest in property, has acted on that belief to their own detriment, and would suffer injustice if the other person were allowed to go back on it.

It applies most often to land, and in a probate context it typically arises where a will fails to reflect a promise the deceased made while alive. Unlike most claims about property, it does not require a contract, a deed, or anything in writing.

The elements of a claim

A claim rests on three elements, with a fourth question running through all of them:

1. Assurance. A promise or assurance, express or implied, that the claimant has or will have an interest in the property.
2. Reliance. The claimant acted on that assurance in a way they would not otherwise have done.
3. Detriment. They suffered detriment as a result. It need not be financial, but it must be substantial.
4. Unconscionability. Standing back, would it be unconscionable to allow the promise to be repudiated?

These are not separate hurdles to be cleared one at a time. In Gillett v Holt [2001] Ch 210 the Court of Appeal held that the doctrine cannot be treated as subdivided into three or four watertight compartments: the quality of the assurance affects whether reliance was reasonable, reliance and detriment are often intertwined, and unconscionability runs through the whole analysis.

Who has to prove what

The claimant bears the burden, on the balance of probabilities. In practice, once a clear assurance and detriment are established, the court will readily infer reliance, and it then falls to the defendant to show the claimant did not in fact rely on the promise.

Where these claims come from

The classic case is the family farm: a son or daughter works for years on low wages, turning down other opportunities, because they have been told the land will be theirs. But the doctrine is not confined to farming. Common situations include:

• A parent tells a child they will inherit the family home, and the child spends years and their own money maintaining and improving it.
• A relative gives up work, or puts a career on hold, to provide unpaid care in return for an assurance about the house.
• Someone contributes substantially to the cost of renovating a property on the understanding it will pass to them.
• A person works unpaid or underpaid in a family business on the strength of a promise about its premises or land.

What these have in common is a long period of reliance that cannot easily be undone, and an assurance that was never written down. Where the estate includes a farm or other high-value land, and the will does not match what was said, a claim frequently follows. Our guide to inherited property split between siblings covers a related source of family conflict.

How it differs from promissory estoppel

The two are regularly confused, and the difference decides whether you have a claim at all.

Promissory estoppel operates only where there is already a legal relationship between the parties, usually a contract, and it prevents one side enforcing strict rights under it after promising not to. It works only as a defence, and it generally suspends rights rather than extinguishing them.

Proprietary estoppel needs no pre-existing relationship, concerns an interest in property, and can be used to bring a claim in its own right. For an inheritance dispute, it is almost always the one that matters. Our separate guide to promissory estoppel in contentious probate explains where that doctrine does have a role.

What the court can award, and why it may be less than you expect

This is the part that has changed most, and older guidance is unreliable on it.

The remedy is discretionary. The court is not enforcing a contract, so it is not obliged to hand over what was promised. Its task is to prevent or undo the unconscionable conduct involved in repudiating the promise.

The Supreme Court set out the modern approach in Guest v Guest [2022] UKSC 27. The court will normally start from the assumption, expressly not a presumption, that the simplest way to remedy the unconscionability is to hold the promisor to the promise. That starting point is then tested against proportionality, weighing the detriment suffered against any benefits the claimant received along the way. And where the remedy delivers early what was promised for later, the award is discounted to reflect accelerated receipt.

So the expectation is the starting point, not the entitlement.

The leading cases

Gillett v Holt [2001] Ch 210

Mr Gillett worked for Mr Holt for nearly 40 years, from the age of 16, on repeated assurances that he would inherit the farming business. He left school early, tied his entire career to it, and was eventually dismissed and cut out of the will.

The Court of Appeal held that assurances repeated over many years can cumulatively amount to a clear promise, and that his reliance was life-changing. He was awarded the freehold of The Beeches, a farmhouse and around 103 acres, together with £100,000 to compensate for his exclusion from the rest of the business. The case remains the authority for treating the elements in the round rather than in isolation.

Jennings v Rice [2002] EWCA Civ 159

Mr Jennings started as a part-time gardener for Mrs Royle in about 1970 at 30p an hour, gradually took on errands and odd jobs, and from the late 1980s was not paid at all. For the last few years of her life he stayed nearly every night at her house caring for her. She told him he would be “all right” and that the house “would be his one day”, but never put anything in writing.

He sought the house and furniture, worth £435,000, or alternatively the whole estate. The trial judge awarded £200,000 and the Court of Appeal upheld it. The case is the leading authority on proportionality: the award represented what was needed to satisfy the equity, not a windfall measured by the size of the estate.

Thorner v Major [2009] UKHL 18

David Thorner worked unpaid on his father’s cousin’s farm for nearly 30 years. There was never an express promise. The assurance was built up through oblique remarks and conduct over decades, including the handing over of an insurance policy bonus notice with a comment about death duties.

The House of Lords held that an assurance need not be explicit. It is enough that it was “clear enough” to the person it was addressed to, judged in the context of that particular relationship. The appeal was allowed and Mr Thorner received the beneficial interest in Steart Farm. This is the case to cite where the promise was never spelled out.

Guest v Guest [2022] UKSC 27

Andrew Guest left school at 16 and worked on his parents’ Monmouthshire dairy farm for 33 years on low wages, expecting to inherit a substantial share. After a family falling-out the partnership was dissolved and his parents made new wills cutting him out.

He won at trial and the judge ordered an immediate payment of about £1.3 million, which would have forced a sale of the farm. The Court of Appeal upheld it. His parents then appealed to the Supreme Court, and their appeal was allowed in part, by a majority of three to two, with Lord Briggs giving the leading judgment and Lord Leggatt dissenting.

The Supreme Court replaced the award with a choice for the parents: either put the farm into trust for the children, subject to a life interest in their own favour, or pay compensation now with a sufficient discount to reflect Andrew receiving it years earlier than he otherwise would have.

It is worth being precise about this, because it is widely reported as a straightforward win for the claimant. Andrew Guest established his claim, but the Supreme Court decided the courts below had been too generous in how they satisfied it.

Cleave v Cleave [2024] EWHC 2492 (Ch)

A recent illustration from a 52-acre Devon farm, where a son who had worked the land for more than 37 years on low pay succeeded in a proprietary estoppel claim against his 91-year-old mother, alongside disputes about a trust deed and a land transfer.

The case is instructive on a practical problem the older authorities do not address: how to frame a remedy when the promisor is elderly and has her own care costs to meet. The court retained the farmhouse, orchard and paddock for the mother against those costs while awarding the son the bulk of the farmland.

The evidential problem

These claims are hard to prove. The assurance is usually oral, sometimes only implied, and the person who gave it has died. The detriment may be spread over decades and difficult to quantify.

What helps: contemporaneous letters, cards and messages; witness statements from anyone who heard what was said; accounts, payslips or tax records showing what the claimant was actually paid; evidence of opportunities turned down; and records of money spent on the property. Diaries and informal notes carry more weight than people expect.

Courts look at the whole picture, including benefits the claimant received. Living rent-free, or drawing an income from the business, will be set against the detriment claimed.

The lesson for anyone making a will

Most of these cases were avoidable. Where a promise has been made, it should be recorded, and the will should reflect it or explain why it does not. Anyone taking will instructions should ask directly whether assurances have been given about property, because a promise the testator has half-forgotten can undo the whole estate plan.

If you are an executor facing a claim

A proprietary estoppel claim can arise mid-administration and change how the estate is distributed. A few practical points:

Take advice as soon as a claim is intimated. The doctrine is fact-sensitive and the law on remedy moved significantly in 2022.

Stay neutral. Your duty is to the estate, not to any beneficiary, and being seen to take sides invites a challenge to your own position. See the duties of an executor.

Do not distribute while a claim is live. Distributing in the face of a known claim can leave you personally exposed.

Consider mediation early. These disputes are family disputes, the costs escalate quickly, and they are well suited to settlement. Our guide to contentious probate explains the process.

Other claims that may run alongside

A proprietary estoppel claim is often pleaded together with a claim under the Inheritance (Provision for Family and Dependants) Act 1975, which allows certain categories of applicant to seek reasonable financial provision whether or not any promise was made. See how to make an Inheritance Act claim and successful and unsuccessful claims.

That Act has a strict time limit of six months from the date representation was first taken out, so it should be considered early even if estoppel is the main claim. Our guide to Inheritance Act time limits explains the court’s discretion to allow a late claim.

Where the concern is the validity of the will itself, see contesting a will. To stop a grant issuing while you investigate, see the probate standing search, and to obtain the will, how to get a copy of a will.

Getting advice

A contentious probate solicitor can assess the strength of a claim, assemble the evidence, advise on the realistic range of outcomes and negotiate a settlement. Given how much these cases turn on their facts, and how much the remedy can vary, that assessment is worth getting early.

You can find a contentious probate solicitor through The Probate Network and book a free initial consultation.

Frequently asked questions

What is proprietary estoppel in simple terms?

It is a way of enforcing a promise about property that was never put in writing. If someone assured you that you would get their land or house, you relied on that assurance and suffered real detriment as a result, and it would now be unconscionable to let them go back on it, the court can step in. It is the main legal route for someone promised an inheritance that the will does not deliver.

Does the promise have to be in writing?

No. The assurance can be spoken, or implied from conduct over many years. Thorner v Major confirmed that it need not be explicit, provided it was clear enough to the person it was addressed to, judged in the context of their particular relationship. A written record makes the claim far easier to prove, but its absence is not fatal.

If I win, do I get what I was promised?

Not necessarily. Since Guest v Guest in 2022, the court starts from the assumption that holding the promisor to the promise is the simplest remedy, but that is an assumption rather than a presumption. It is tested against proportionality, and where you receive the benefit earlier than promised the award is discounted for accelerated receipt. In Jennings v Rice the claimant sought a house worth £435,000 and received £200,000.

What did Guest v Guest actually decide?

Andrew Guest established his claim, but the Supreme Court allowed his parents’ appeal in part and replaced the £1.3 million immediate payment ordered below with a less generous remedy. The parents may choose either to put the farm into trust for their children while keeping a life interest, or to pay compensation now, reduced to reflect early receipt. It is often described as a win for the claimant, which understates what the Supreme Court changed.

How is this different from an Inheritance Act claim?

Proprietary estoppel depends on a specific promise about property and requires assurance, reliance and detriment. An Inheritance Act claim depends on your relationship to the deceased and your financial need, and no promise is required. The categories of person who can bring an Inheritance Act claim are limited, while estoppel is open to anyone who was given an assurance. The two are frequently run together.

How long do I have to bring a claim?

There is no fixed statutory period for proprietary estoppel. Equitable relief can instead be refused on the grounds of laches, meaning unreasonable delay that causes real prejudice to the other side, or acquiescence. Because there is no clear deadline, and because evidence in these cases depends on memory, the practical advice is to act quickly. If an Inheritance Act claim may also be available, the six-month limit there governs the timetable.

This article is for general guidance only and applies to England and Wales. It does not constitute legal, tax or financial advice. The law can change and every case turns on its own facts. For advice on your own circumstances, speak to a qualified solicitor. You can book a free legal consultation through The Probate Network.