T sold a vacant plot of land in Leicester Square to E. E covenanted that he, his assignees and his heirs would “keep and maintain” the land in an open state, uncovered with any buildings. M later received the land and threatened to build on it, against which T sought an injunction. This was granted by HL.
Lord Cottenham LC: If a Purchaser buys with notice of a prior undertaking to treat the land in some way, it would be inequitable for him not to so treat it. This contrasts with general common law of privity of estate. He draws no distinction between negative or positive easements. “Nothing could be more inequitable than that the original purchaser should be able to sell the property the next day for a greater price, in consideration of the assignee being allowed to escape from the liability which he had himself undertaken.” Were this merely a common law agreement (e.g. if T were suing for damages) there could be no remedy, but since an equitable remedy is sought (injunction) the court can intervene to prevent inequitable conduct.