unenforceable for want of consideration. Denning commented that such an agreement should now be enforceable under the doctrine of promissory estoppel, and indeed the plaintiff did not seek the full debt on the basis of what was fair and, perhaps, thought was the law. However, the courts were at first reluctant to overrule or distinguish cases like Pinnel's case and Foakes v Beer having formed part of the common law for so long. Lady Justice Arden in Collier v P & MJ Wright (Holdings) Ltd (2007) accepted in principle that High Trees could be used to extinguish a creditor's right to full payment of a debt in such circumstances. In Amalgamated Investment Co v Texas Bank it was decided that proprietary estoppel can act as a sword and not merely as a shield (that is, it can be used as a cause of action rather than merely providing a defence to an action). See also Estoppel Promise References Lord Denning cases English enforceability case law English estoppel case law 1946 in British law High Court of Justice cases 1946 in case law