An unsuccessful disputed wills case - a broken promise

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What is proprietary estoppel?

Although there is no definition that is both 'comprehensive and uncontroversial', the doctrine of Proprietary Estoppel has underpinning elements that must be considered by the Claimant when bringing a claim under this basis, these are:

The Promise

The claimant must show that there was a promise made to them.  A promise can be in the form of a representation and/or an assurance.  Such examples are often found in the agricultural sector, for instance, a father may say to his son 'continue the hard work and the farm is yours'. 

The Reliance

Once a promise has been made, the claimant must then reasonably rely on that promise.

The Detriment

The third element to any propriety estoppel claim is detriment.  In reasonably relying on a promise made, the claimant must have suffered some form of detriment.  A classic example of detriment would be financial - for example low (or no) pay, or giving up a more financially rewarding alternative career - however, detriment may take shape in many forms.


Finally, it must be unconscionable for the promisor to be permitted to resile from his or her promise.

Once a claim has been established, the Court will then determine how best to satisfy the equitable right that has arisen. The Court will look to do justice.

Not all promise, reliance and detriment cases will give rise to a successful proprietary estoppel claim.

McDonald -v- Rose [2019] EWCA Civ 4

The claimant, Gary McDonald, claimed that his parents had assured him over numerous years that he would receive the bulk of their estate should he keep working on the family farm.  Mr McDonald claimed that he had in fact carried out such work in reliance on such assurances and that it would be unconscionable for his parents’ estates not to give effect to those assurances. However, his five siblings resisted his claim. 

The Defendants claimed that they were a ‘close-knit family’ and no child was favoured above and beyond any of the other siblings.  They also asserted that each sibling had been told on several occasions that they would all share in the estate. A significant number of witnesses, including some third parties, were able to give their account of events which all strongly supported the Defendants' position.

The decisive factor in this case was the substantial amount of reliable witness evidence (including from non family members) produced by the Defendants. The judge also noted that as Mr McDonald had since 2006 managed his own successful business, during which time he did not work on the farm, this was not a case of a family member working their whole life on the farm for little recompense.

The Judge concluded that Mr McDonald’s parents had not given the assurances as alleged, and he dismissed Mr McDonald’s claim. The Court of appeal upheld that decision.


This case reinforces the requirements of showing each of the key elements, promise, reliance and detriment and that each strand of the claim is interlinked. 

There are no hard and fast rules as to what will amount to a promise, but the Court will balance all the strands of the claim in order to determine whether an estoppel is made out. Witness evidence from third parties with nothing to gain personally, will make a significant difference to the strength of the arguments either way.

If you would like help on bringing or defending a claim in proprietary estoppel, please contact our Disputed Wills and Trusts Team by telephone on freephone 0800 0931336, or by email at  for a non-obligatory chat to see how we can help you.

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