This is one of the patronymic forms of the early medieval English surname Clark(e) or Clerk(e). The surname is an occupational term for a scribe or secretary, or in some cases for a member of a minor religious order, derived from the Olde English pre 7th Century "clerec, clerc", priest, reinforced by the Old French "clerc", introduced after the Norman Conquest of 1066, and both derived from the Latin "clericus". The word "clerc" originally meant only a member of a religious order, but since the clergy of minor orders were permitted to marry, and so to found families, the surname became established in the early Middle Ages. The term "clerk" gradually came to be used of any literate man, particulary professional secretaries, since virtually all the population in medieval Europe were unable to read or write except members of a religious order. The patronymic forms of Clark(e) are Clarkson, Clarson and Clarkstone. One Ralph Clarkson is recorded in the Register of the Guild of the Corpus Christi in the City of York for 1491. The first recorded spelling of the family name is shown to be that of Alan le Clerkissone, which was dated 1306, in the "Feet of Fines of Suffolk", during the reign of King Edward 1, known as "The Hammer of the Scots", 1272 - 1307. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.