# Promissory estoppel

> **Key takeaway:** Clear promise + reliance + inequitable to resile (Hughes; High Trees). Usually suspensory. Shield not sword (Combe). Distinct from consideration and proprietary estoppel. Notice may revive rights (Tool Metal).

- **Jurisdiction:** England & Wales
- **Practice area:** Commercial
- **Last reviewed:** 2026-08-04
- **Interactive page:** https://kttclegal.info/library/notes/Commercial/promissory-estoppel
- **Keywords:** promissory estoppel, High Trees, Hughes v Metropolitan Railway, Combe v Combe, waiver, suspensory, reliance, equity

## What is this about?

Promissory estoppel can suspend (and in limited circumstances affect) strict contractual rights where a party has made a clear promise that the other has relied on. It is a shield more than a sword in orthodox English doctrine and interacts carefully with consideration.

## What is the core rule?

Where parties are in a legal relationship and one makes a clear and unequivocal promise not to enforce strict rights, intending it to be relied on, and the promisee relies on it in a way that makes it inequitable to resile, the promisor may be estopped from enforcing those rights inconsistently with the promise (Hughes v Metropolitan Railway; Central London Property Trust v High Trees). Typically it suspends rights rather than extinguishing them forever, and cannot usually create a new cause of action where none existed (Combe v Combe), though the boundaries with proprietary estoppel and waiver are fact-sensitive.

## What are the elements or test?

1. Existing legal relationship (usually contractual)?
2. Clear promise or representation as to present/future rights?
3. Reliance by the promisee?
4. Inequitable to go back on the promise?
5. Scope: suspensory or extinctive on these facts?
6. Is the claimant trying to use estoppel as a sword (Combe problem)?

## Which authorities matter?

- **Hughes v Metropolitan Railway Co (1877) 2 App Cas 439** — Foundational equitable estoppel suspending strict rights after a representation.
- **Central London Property Trust Ltd v High Trees House Ltd [1947] KB 130** — Modern promissory estoppel classic — wartime rent reduction promise.
- **Combe v Combe [1951] 2 KB 215** — Promissory estoppel is a shield not a sword — cannot found a cause of action alone in orthodox doctrine.
- **Tool Metal Manufacturing Co Ltd v Tungsten Electric Co Ltd [1955] 1 WLR 761** — Suspension may end on reasonable notice in appropriate cases.

## How does this apply in practice?

Distinct from proprietary estoppel (land assurances) and from consideration/variation (Williams v Roffey). Part-payment of debt still engages Foakes v Beer — estoppel may assist on different facts (High Trees style). Always plead inequity of resiling with evidence of reliance.

## What are common pitfalls?

- Using promissory estoppel to create a contract without consideration as a free-standing claim
- Vague 'understandings' that are not clear promises
- Ignoring the suspensory nature and notice to resume rights
- Conflating with proprietary estoppel remedies

## When would a practitioner use this?

Rent concessions, standstill arrangements, and disputed variations without formal consideration.

## Quick reference

Clear promise + reliance + inequitable to resile (Hughes; High Trees). Usually suspensory. Shield not sword (Combe). Distinct from consideration and proprietary estoppel. Notice may revive rights (Tool Metal).

---

*Reference material from [KTTC Legal](https://kttclegal.info/), not legal advice. Work product supports instructing solicitors and barristers under their supervision. England & Wales.*