The recent case of HX v WX [2025] EWFC 338 (B) offers a textbook example of how third-party interests—often involving family members—are determined within financial remedy proceedings. Here, District Judge Davies grappled with whether a 92-year-old mother-in-law, referred to as IX, had an equitable interest in her daughter’s former matrimonial home after funding the construction of an annexe in which she lived.
The judgment provides practical insight into how proprietary estoppel claims are treated when family finances and property mix, and it also highlights the importance of proper pleadings and evidence when third parties are joined to financial remedy cases.
The Facts: Family Ties and Financial Contributions
The former matrimonial home was jointly owned by husband (HX) and wife (WX). In 2020, IX sold her own cottage and paid around £176,000 for an annexe to be built at the property, intending to live there for life. The parties agreed she would have a “home for life,” and IX moved in the following year.
After the couple’s separation, relations deteriorated and IX claimed that, having spent over £211,000, she was entitled not just to occupy the annexe but also to a share of the property. She argued she had relied on assurances from both HX and WX, suffered detriment, and that it would be unconscionable for them to retain the benefit of her contribution without recognition of her equity.
The Law: Establishing a Third-Party Interest
The court applied the TL v ML [2005] EWHC 2860 (Fam) framework for intervenor claims within financial remedies and the familiar three-part test for proprietary estoppel:
- Assurance or representation – a promise or understanding that creates an expectation of an interest;
- Reliance – the claimant acts on that promise;
- Detriment – the claimant suffers loss or disadvantage by doing so.
If those elements are proved, the court must fashion an equitable remedy that prevents unconscionability—though not necessarily granting the full amount spent or a proportional share.
The Outcome: An 18% Interest and a Life Interest
HX conceded during the hearing that IX had a life interest, but denied any ownership share. District Judge Davies disagreed, finding all elements of proprietary estoppel were satisfied. However, instead of awarding a pound-for-pound reimbursement, the court grounded its remedy in fairness and proportionality.
Based on evidence that IX’s contribution enhanced the home’s value by £100,000, the judge held that she was entitled to an 18% beneficial interest, alongside her right to live there for life. Following delivery of this judgment, all parties came to terms to conclude matters by consent.
Practical Lessons: The Path for Intervenors
This case is a useful reminder that when a third party—often a parent—claims an interest in a matrimonial home, the court will:
- Require formal pleadings (points of claim and defence) per TL v ML;
- Expect clear evidence of the alleged agreement or promise;
- Focus on detrimental reliance and the equitable balance of fairness;
- Avoid granting automatic reimbursement, instead fashioning a remedy that reflects the reality of the parties’ intentions and contributions.
Why It Matters
Intervenor claims are increasingly common as family wealth is shared across generations, often without formal documentation. HX v WX underscores that equity protects fairness, not generosity—and that where family contributions enhance value or create expectations, the court will step in to prevent injustice.
For practitioners, the case illustrates the need to identify and manage third-party interests early in proceedings and to ensure the evidence satisfies the strict criteria of proprietary estoppel.
