This is a baptisimal name 'the son of Piers' ie. Peter, from the French 'Pierre' of the Olde English Pearse or Piers. A name which means 'rock'. In the modern idiom the name has four spelling variations Pearson, Pierson, Peirson and Pirson. The first form Pearson was introduced into Ireland mainly in the 17th century and became very numerous in Leinster in the 18th century. It is now found in many parts of the country. The first recorded spelling of the family name is shown to be that of Walter Peressone. which was dated 1327 Kirby's Quest of Sommerset. during the reign of Edward 111 The Father of the Navy 1327 - 1377. 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.