This interesting surname, with the modern variants O'Duilleain, Dilon, Dillane and Dilks, has two possible origins. The first being locational "of Dilwyn" in Herefordshire, recorded as "Dilun" in 1138, and deriving from the Olde English pre 7th Century "diglum", a retreat. Locational surnames were usually acquired by a local landowner, or by the lord of the manor, and especially by those former inhabitants of a place who had moved to another area, and were thereafter best identified by the name of their birthplace. A second possibility is that the name derives from a Germanic personal name "Dillo", meaning "the destroyer", introduced into England by the Normans after the Conquest of 1066. The Dillons came to Ireland at the time of the Anglo-Norman Invasion of 1169. In Ireland, the name is a transposition of de Leon, or an Anglicization of the Gaelic name "O'Duilleain", meaning "descendant of the blind one". They gave their name to Dillon's Country in County Westmeath. The first recorded spelling of the family name is shown to be that of Geoffrey Dilun, which was dated 1203, in the "Select Pleas of the Crown", Shropshire, during the reign of King John, known as "Lackland", 1199 - 1216. 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.