This notable Welsh surname is a patronymic form of the medieval male given name "Ble(i)ddyn", originally a byname meaning "wolf cub", from "blaidd", wolf, plus the diminutive suffix "yn". Heroes of medieval Wales were often referred to as "Blaidd", although the term was also something used to describe a cruel man, or one who pretended friendship while remaining an enemy. The name is much associated with early Welsh royalty, Bleddyn ap Cynfyn being an 11th Century prince in Gwynedd (North Wales), and Bleddyn Fardd, who flourished circa 1268, was one of the princes' poets. It is recorded that "At the Survey (Domesday Book, 1086), Alan, son of Flaald, obtained the manor and castle of Oswaldstrey (Oswestry) in Shropshire, which belonged to Meredith ap Blethyn, a Welshman or Briton, by gift from William the Conqueror". The forms Plevin, Pleavin, Pleven and Pleaden result from the "p" of the patronymic prefix "ap" being absorbed into the name. One John ap Plethin and a Robert Plethyn were mentioned in Wills Records of Llandegveth (Monmouthshire) and Flintshire in 1542 and 1551 respectively, and on February 14th 1584, the marriage of Margery Pleavin to Christopher Sherly took place at St. Olave's, Hart Street, London. The first recorded spelling of the family name is shown to be that of David ap Plethyn, which was dated 1391, in "Medieval Records of Chirk", Wales, during the reign of King Richard 11, known as "Richard of Bordeaux", 1377 - 1399. 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.