Guest & Anor v Guest

Factual and Procedural Background

Plaintiff is the eldest child of the Defendants, who own and operate “The Farm,” a 197-acre dairy enterprise. From 1982, Plaintiff worked on the family holding for low wages, relying on repeated assurances from Defendant 1 (with the tacit support of Defendant 2) that he would inherit a “substantial stake” in the land and business after both parents died. Relations deteriorated in 2014; the Defendants revoked earlier wills, dissolved their farming partnership with Plaintiff in 2015, and required him to vacate a cottage on the property. Plaintiff commenced proprietary-estoppel proceedings in 2017.

The trial judge (Judge Russen) found the estoppel established and ordered the Defendants to pay an immediate lump sum of c. £1.3 m (net of tax) calculated as 50% of the dairy business and 40% of the land value, less a life interest in the farmhouse. The Court of Appeal upheld that order. The Supreme Court (Judges Leggatt, Stephens, Briggs and others) granted further appeal limited to remedy.

Legal Issues Presented

1. What principle justifies equitable relief when the elements of proprietary estoppel (assurance, reasonable reliance, detriment) are proved?
2. In remedying such claims, should a court prioritise fulfillment of the claimant’s expectation (what was promised) or compensation for reliance (the detriment suffered)?
3. How should the court proceed where an inheritance-based assurance is revoked during the promisor’s lifetime and the promisee has already incurred detriment?
4. Did the trial judge err, in law or discretion, by awarding an accelerated lump-sum expectation-based remedy that forced an immediate sale of the family farm?

Arguments of the Parties

Defendants’ Arguments (Appellants)

• Equitable relief should start from the promisee’s reliance loss; here that would be limited to lost earnings/opportunity, not the value of the promised land.
• The judge wrongly “accelerated” an expectation payable only on death, compelling a premature sale and disproportionate tax liabilities.
• An immediate award ignored alternatives such as tenancy or staged payments and exceeded the “minimum equity” to do justice.

Plaintiff’s Arguments (Respondent)

• The doctrine is “animated by expectation”; the norm is to satisfy the promise unless obviously disproportionate.
• Decades of unquantifiable detriment (low wages, life-changing commitment) justified a clean-break, accelerated award.
• The percentages chosen broadly mirrored earlier wills and achieved fairness amid a total family breakdown.

Table of Precedents Cited

Court's Reasoning and Analysis

Judge Leggatt (majority) re-examined proprietary-estoppel relief. Key analytical steps were:

1. Doctrinal foundation. The “equity” arises to prevent detriment where a promisee reasonably relies on a non-binding assurance. It is not enforced simply to make people keep informal promises.
2. Dual remedial tools. Detriment may be avoided either by (a) fulfilling the promise (expectation) or (b) compensating reliance loss. Courts must choose the minimum remedy sufficient to avert detriment.
3. Proportionality. A remedy matching the promise is improper where value is “out of all proportion” to reliance. Seminal authorities (Gillett, Jennings) require careful calibration.
4. Conditional promises. Where an inheritance promise is revoked in the promisor’s lifetime, acceleration and contingencies must be discounted; often reliance compensation is fairer.
5. Application to facts. The trial judge awarded c. £1.3 m based on anticipation of half the business and 40 % of land. He gave no clear reasons for the chosen percentages, failed to discount for acceleration, and did not analyse Plaintiff’s actual detriment.
6. Re-assessment. Supreme Court (majority) quantified Plaintiff’s lost earnings from 1990–2015, grossed-up, then added compound interest (2 % over base) to reach an equitable figure of £610,000. This sum represents realistic compensation for reliance without over-rewarding expectation.

Holding and Implications

Held: The appeal is allowed. The High Court’s lump-sum order is set aside and replaced with an award of £610,000 payable immediately by the Defendants to the Plaintiff.

Implications: The Supreme Court clarifies that proprietary-estoppel remedies must centre on avoiding detriment; proportionality is paramount. Courts should prefer reliance-based compensation where expectation-based awards would accelerate inheritances or prove excessive. The judgment provides structured guidance, likely to curtail inconsistent, “palm-tree” decisions and to encourage parties to make early, reasonable compensatory offers when informal succession plans unravel.