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Equity

England & Wales

Promissory estoppel

The rule

Where one party to a contract makes a clear and unequivocal promise, intended to be acted on, that they will not enforce their strict legal rights, and the other party acts on that promise, equity may estop the promisor from going back on the promise to the extent it would be inequitable to do so.

Mandatory cases

Curated chronological

1. 01

   Hughes v Metropolitan Railway Co · 1877

   (1877) 2 App Cas 439 · House of Lords Procedural posture

   Appeal from the Court of Appeal allowed; the lessor was estopped from forfeiting on the basis of a notice that the tenant had been induced to ignore.

   The doctrinal seed, equity will not allow a party who has lulled another into a course of conduct to insist on strict rights.

   What cuts the other way

   Hughes only suspends rights; the promisor can usually resume strict enforcement on reasonable notice, so estoppel rarely extinguishes the underlying obligation outright.

2. 02

   Central London Property Trust Ltd v High Trees House Ltd · 1947

   [1947] KB 130 · King's Bench Procedural posture

   Action in the King's Bench Division; judgment for the landlord on the post-war rent, with Denning J's estoppel analysis given as obiter dicta.

   Denning J's reformulation that gave the modern doctrine its name and its most-cited illustration.

   What cuts the other way

   Denning's reasoning was strictly obiter; later courts treat it as authoritative but defendants may argue its true ratio is narrow and confined to a temporary wartime concession.

3. 03

   Combe v Combe · 1951

   [1951] 2 KB 215 · Court of Appeal Procedural posture

   Appeal from the King's Bench Division allowed; the wife's claim on the husband's maintenance promise failed for want of consideration.

   Established that promissory estoppel is a shield, not a sword, it suspends rights but does not create a fresh cause of action.

   What cuts the other way

   The shield-not-sword rule is rejected in some Commonwealth jurisdictions (e.g. Waltons Stores (Interstate) Ltd v Maher (1988) 164 CLR 387 in Australia); only English authority binds you in this jurisdiction.

4. 04

   D & C Builders Ltd v Rees · 1966

   [1966] 2 QB 617 · Court of Appeal Procedural posture

   Appeal from the County Court dismissed; the builders recovered the balance of the debt.

   Inequitable conduct by the promisee defeats reliance on estoppel, required for any complete answer on its limits.

   What cuts the other way

   Inequitable conduct must be proved on the facts; ordinary commercial pressure or hard bargaining does not bar a debtor from reliance on estoppel.

Run a real argument through LexCases

A landlord agreed to halve the rent during a downturn, then sued for the arrears once tenants returned to the building. Build the strongest defence using promissory estoppel.

LexCases will run the argument against current case law and rank the cases, including these foundations and any later cases that have built on or pulled away from them.

Curated for England & Wales. Always verify each case before relying on it in formal work. Citations are accurate at the time of publication, but the law moves.