Many surnames are quite obviously occupational and recall the trade carried out by your ancestor. Indeed any dictionary of surnames is also a list of all the common trades of this country in the Middle Ages, many of which are now extinct or rarely encountered. They fall into broad categories such as agricultural, (Farmer, Herd) manufacturing (Smith, Wright) and trade (Merchant, Mercer). There are other similar names involving status and the roles of supporting and serving staff which come into this category such as Abbott, Clark, Squire, Bond (peasant farmer). Since almost every village would have its own Smith and Miller it stands to reason that identically named persons in one place were not necessarily related to those in another.