This ancient name is of English locational origin from the port of Kent thus called. Recorded variously as "Dubris", circa 425 A.D., as "Dofras" in the Anglo-Saxon Chronicle, dated 696 - 716, and as "Doferum", circa 100, in "The Saints of England", edited by Liebermann, the place was so named from the river on which it stands, now called Dour, but originally named with the British "Dubra", from "dubra", water, which became the Welsh "dwfr", water. ("British", in this case, refers to the extinct Celtic language of the ancient Britons, and the name means "the waters", i.e. "the stream"). The surname from this source was first recorded in the latter part of the 11th Century (see below). Other early recordings include John de Dover, witness in the 1223 Fine Court Rolls of Kent, and Hugo de Dovre, in the Hundred Rolls of Wiltshire (1273). An interesting namebearer was Thomas Dover (1660 - 1742), physician, who sailed as captain of the "Duke" on a privateering voyage, and rescued Alexander Selkirk from the island of Juan Fernandez. The first recorded spelling of the family name is shown to be that of Theoloneus de Doure, which was dated 1086, in the Domesday Book of Kent, during the reign of King William 1, known as "The Conqueror", 1066 - 1087. 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.