Proprietary estoppel

Proprietary Estoppel


X assures Y of future rights in land and Y relies on the assurance and acts to his detriment.

The Representation

•  Must relate to present or future rights in land.

•  Promises must be clear and unequivocal but can be made by silence.

•  Promises of rights under a will cannot be relied on unless they are clear and have been relied on by the claimant over a long period of time.


•  Claimant must show a change of position in reliance on the promise.

•  The change of position can be quantified in money terms or contributions of labour but must no1 be inconvenience or altered lifestyle.

•  The detriment may be suffered by someone other than the claimant.


•  The representee must be shown to be unconscionably disadvantaged by relying on the promise.

•  There may be bars to a claim if the claimant did not act equitably i.e. with ‘clean’ hands.

Nature of the Rights Arising

•  Entitles the claimant to equitable relief.

•  The right can be entered on the register under s116 LRA 2002; can be an overriding interest.

•  Can be binding on third parties.

6.1 Definition of Proprietary Estoppel

1.  X, the owner of land, expressly or impliedly gives an assurance to Y respecting present or future rights in land, and Y relies on that assurance acting to his detriment.

2.  Proprietary estoppel used to depend on the proof of five probanda under Willmot v Barber (1880):

i)    claimant of an equity makes a mistake about his/her legal rights;

ii)   on the basis of the mistake the claimant acts to his/her detriment by spending money or carrying out some act;

iii)  knowledge by the possessor of the legal right of the other party’s belief;

iv)  knowledge by the other party that the belief is mistaken;

v)   the other party must have encouraged the claimant in the expenditure incurred.

3.  Today the definition of proprietary estoppel depends on three elements:

   a representation (or assurance of rights);

   reliance (or a change of position);

   detriment (or unconscionable conduct).