Now that Article 50 of the Treaty on European Union has been triggered and negotiations regarding the withdrawal of the United Kingdom from the European Union are underway, the state’s departure from the Union is becoming a reality. However, even if this process is finalised, it is important to draw attention to the fact that the United Kingdom’s past contribution to the European project remains crucial and will maintain its relevancy in the future. The preliminary ruling procedure has been an invaluable tool for shaping and developing EU law, and the United Kingdom’s withdrawal does not render void any of the rulings pronounced by the Court of Justice in answer to questions referred by British courts, rulings that have had a direct influence over the internal law of all Member States. In consideration of the essential role of the preliminary ruling procedure, this paper will present several instances where the judicial authority of the European Union was called upon to offer an interpretation on the compatibility of the United Kingdom’s legislation with EU law and, by answering the questions referred by the British courts, established a binding precedent for the national courts of all Member States and furthered the process of judicial integration.