On 19th October 2022, the Supreme Court handed down its much-anticipated judgment in Guest and another v Guest. Here the court addressed the proper basis for awarding remedies in cases of proprietary estoppel.


“One day my son, all this will be yours”. These words were spoken on numerous occasions and repeated over the years from a father to his son. The son relied on this promise of inheritance spending thirty-two years working and living on the family farm, expecting, one day, to inherit the farm from his father. However, the relationship broke down to such an extent that not only do they now find it impossible to work together but they cannot live within close proximity of one another. The son had no alternative but to leave, find alternative work and rent accommodation for himself and his family elsewhere. Meanwhile, the father cut his son out of his will.

The facts of Guest and another v Guest differ somewhat from the typical example of this kind of case in that the father has two sons as well as a daughter. Therefore, it was not the whole of the farm that was promised but only a sufficient (but undefined) part to enable him to operate a viable farming business on it after the death of his parents.

The trial judge concluded that, until the falling out in 2014, the son was consistently led to believe that he would succeed to the farming business and inherit a substantial share of the farm. As to the remedy, the judge described his task as being to exercise a ‘broad judgemental discretion in an endeavour to do what is necessary to avoid an unconscionable result or, alternatively, to identify the minimum equity to do justice.’ The appropriate ‘clean break’ remedy was deemed to be an immediate lump sum payment to the son comprising:

  1. 50% after tax of either the market value of the farming business (as valued in an expert’s report) of the value realised by a sale of the business in consequences of the judgment; plus
  2. 40% after tax of either the market value of the freehold land and building at the farm or of the proceeds of sale in consequence of the judgment. In either case the farmhouse was to be treated as subject to a life interest in favour of the parents;
  3. The amount payable to the son was to be net of any taxes payable by the parents on the sale of the business and/or farm.

The amount payable to the son was £1.3 million. Permission to appeal was granted only on the question of the remedy. The parents argued that the judge was wrong to fashion a remedy based on the son’s expectation of inheritance and should instead have awarded compensation based either on the extent to which the value of the farm had increased as a result of the son’s contribution or his loss of opportunity to work elsewhere.

Principles of proprietary estoppel

Underpinning this remedy is the principle that equity will not let A resile on a promise made without ensuring that B does not suffer detriment because of B’s reliance on it. The aim is thus to prevent detriment to B in the circumstances that have arisen. The estoppel is premised on the doctrine that equity is concerned to prevent unconscionable conduct, and it is that factor which determines whether an award should be made.

As the judgment of the Supreme Court sets out, there are two methods of achieving this aim. The first is to compel A to perform the promise (or award a sum of money calculated to put B into as good a position, as best money can do it, as if A’s promise had been performed). The other is to award a sum of money calculated to put B into as good a position, as best money can do it, as if B has not relied on A’s promise: in other words, to compensate B’s reliance loss. Since both methods will in principle achieve the aim of preventing detriment to B, if on the facts both are practicable the court should adopt whichever method results in the minimum award necessary to achieve that aim.

Or as Lord Briggs put it: ‘the issue which has divided academic opinion is as to the purpose of the equitable remedy. Is it to give effect to B’s expectation, so that B receives what he’s been promised? Or is it to compensate B for the detriment suffered in reliance on it, or is there some different purpose?’

The Court of Appeal

The appeal was heard on three grounds: 1. That the judge was wrong to hold that the appropriate approach to relief was to base the remedy on the son’s subjective expectations; the judge should have gone no further when granting relief than was necessary to avoid an unconscionable result and/or considered what the parents must, in all the circumstances, be taken to have intended in order to avoid and unconscionable result; 2. The relief granted went beyond what was necessary to avoid an unconscionable result, or, in so far as different, the minimum equity to do justice; 3. In so far as any equity is ‘anticipatory’, such that in the current circumstances it would be unconscionable for the parents not to make provision for the son, such equity can be satisfied by the making of a declaration or by the grant of injunctive relief.

The Court of Appeal applied the methodology used in Davies v Davies [2016] EWCA Civ 463. In this case, Lewison LJ suggested that ‘a useful working hypothesis’ was to apply ‘a sliding scale by which the clearer the expectation, the greater the detriment and the longer the passage of time during which the expectation was reasonably held, the greater would be the weight that should be given to the expectation.’ The Court of Appeal found that, although the assurances given to the son were given in broad, descriptive terms, there was no uncertainty of a kind that would assist the appellant parents.

The Supreme Court

The parents further appealed to the Supreme Court. Their argument was that the amount the son was to receive under the order was more than the amount of the detriment suffered and more than the net value of the contribution he made to the farming in excess of what he was paid.

In Jennings v Rice [2002] EWCA Civ 159, Lord Justice Walker put it this way: ‘The essence of the doctrine of proprietary estoppel is to do what is necessary to avoid an unconscionable result, and a disproportionate remedy cannot be the right way of going about that.’ There is no equitable power to give B more than A promised.

In giving the son 40% of the value of the farm now, the trial judge accelerated the date upon which the parent’s promise was to be enforced, as they may have many years to live. There should have been a discount for early receipt. As a clean break had already been achieved, it would not have been unconscionable to place the farm on trust. Thus, the parents should be entitled to choose between two forms of relief: the first being a clean break, as set out by the trial judge, but discounted for early receipt. The second being a reversionary interest under a trust of the farm, with the parents having a life interest in the meantime.


In this case, given the fact that both parents were still alive, an allowance should have been made for acceleration. For example, if the parents were to fall ill or require care services later in life, the promise made to the son would have precluded them from using some of their assets to pay for this. In re-assessing the detriment suffered by the son, the court chose to estimate his reliance loss. The objective was to place the son, so far as money can do it, in as good a position as if he had not built his career on the promises made by his father. Given the typically high capital values of farmland, it was likely the land would be worth far more than any value of detriment in this case. The parties both sought a clean break, and the son was awarded £610,000 as equitable compensation.

The judgment in Guest and another v Guest illustrates the importance of checking, prior to granting a remedy, that the remedy will not be out of proportion to the value of the detriment suffered by the claimant.

Adam Jones