Do you need an existing contractual relationship for promissory estoppel doctrine to apply?

No, an existing contractual relationship is not a requirement for the doctrine of promissory estoppel to apply in English law. The doctrine of promissory estoppel operates as a means of enforcing a promise made by one party, even if the promise does not have all the elements of a formal contract. The doctrine can be used to enforce promises made in a wide range of circumstances, including pre-contractual negotiations, post-contractual dealings, and even where there is no contractual relationship between the parties at all. The key requirement for the doctrine of promissory estoppel to apply is that the promisee must have relied on the promise made by the promisor, and must have suffered a detrimental change of position in reliance on that promise. The absence of a formal contractual relationship does not prevent the doctrine of promissory estoppel from being invoked, as long as the other requirements are met.