Equity

• 1.The representation must be one of existing fact
• 2. The estoppel only acts as a defence (shield not a sword)
• 3. It acts as a complete bar to X's insistence on his legal rights

• - Although it has its basis in estoppel by representation, it does accomodate promises of future intention
• - Operates to stop a promisor from reneging on his promise either if he intended or it was reasonable that the promise was relied upon by the promisee and if the promisee did in fact rely on the promise to his detriment

landlord and tenant. Plaintiff served notice on D to carry out repairs within 6 months. P was estopped from going back on his promise

High Trees 

• 1. Operates as a defence only; not cause of action
• Combe v Combe - 'used as a shield and not a sword'
• However in Re: Wyvern Development Ltd [1974] promissory estoppel applies whenever the promissor knows and intends that the promissee will irretrievably alter his position on the promise

• Walton Stores Ltd v Maher (1988)
• Cullen v Cullen
• Re JR
• Association of GP Ltd v Minister for health

Promissory estoppel only operated in situations involving a pre existing contractual relationship or at least a relationship which gave rise to legal rights and obligations. This does not represent the law in Ireland

Transfer of property to wife so she would not commit him to a mental hospital. son erected a portable house on P's land by his mothers direction and P's consent. P sought an injunction to restrain D's trespass on his land

When property owners encourage others to act to their detriment in the belief that they will be granted an interest in the owners property

• Dillwyn v Llewelyn (1862)
• Father promised land to his son. Son built on the land with his fathers consent and knowledge. An informal memorandum showed that it was the fathersw intention to give the land to the plaintiff. But, the memorandum was not sufficient to transfer the land to P in the way the law required in order to make him the owner of it.
• The gift was imperfect. After the fathers death it transpired that he had left the land on trust to others. House of Lords held fee simple should be transferred to P as there was 
• 1. Assurance
• 2. Reliance 
• 3. Detriment

• Ramsden v Dyson (1866)
• Plimmer v Wellington (1884)
• Inwards v Baker (1965) - dec'd had encouraged his son D to build a house at his own expense on dec'd land

1. Plaintiff must have made a mistake as to his legal rights

2. P must have expended some money or have done some act on the faith of his mistaken belief

3. D, the possessor of legal right, must know of the existence of his own right which is inconsistant with the right claimed by the plaintiff

4. D must know of the plaintiffs mistaken belief of his rights

5. D must have encouraged P in his expenditure of money or in the other acts which he has done either directly or by abstaining from asserting his legal right.