The notion of a "common market" makes sense. The notion that Italians, Germans, and Frenchmen should determine how many hours an Englishman works is just plain nutty.
The problem is, the one inevitably leads to the other. You can't have a system of complete free trade over a certain area without there being nearly irresistable calls for some kind of superintending authority. That's what the "free traders" in our own government understand only too well.