What is the effect of Williams v roffey bros?

Williams v Roffey Bros established the principle that a promise to pay an additional sum for performance of an existing contractual duty can be enforceable if it confers a practical benefit to the promisor. This case clarified that consideration can exist in situations where the performance of a pre-existing duty is modified, thereby allowing parties to renegotiate contracts without needing new consideration. The ruling emphasized the importance of practical benefits in contract law, influencing how courts interpret agreements and enforce promises within existing contractual frameworks.