There are a number of references that discuss a person being given a first name which was followed by "bar" or "ben" and then either the male parent's name or the town in which they were born. Such traditions continued for centuries thereafter. Thus, only a few hundred years ago there may have been a John, son of Raymond or John of Devon. At some point in order to differentiate one John of Devon from yet another, the male parent's occupation - or even their own - may have been added. From this we may have John Smith (of Devon).