So, a simple way of explaining last night's discussion has just popped into my head, which should suit all sides and ensure that other posters who were reading that discussion aren't left confused.
Say you have a simple loan contract with somebody, where you are due to repay them £10,000 in five years time. But you agree between you that you will pay £6,000 immediately to settle it. That payment completely wipes out the existing debt.
But say instead you have a contract where that five years has expired, and the payment of £10,000 is due
immediately, and you cannot pay. The other side might agree to accept £6,000 in full and final settlement. In this situation, however, the debt is not wiped out. You still owe the balance of £4,000. The question then is whether that £4,000 can be pursued at a later date through the courts. And that is where promissory estoppel comes in. Even though the £4,000 is
legally owing, a court might decide that it is
unfair to allow the other party to recover it.
@motorbiking