Double-barrelled surnames, usually created following a marriage between two families, have no overall meaning as a unit, but the separate parts have their own meaning and derivation. In this instance, the name Erskine is of medieval Scottish origin, and is a locational name from Erskine, a parish on the south bank of the river Clyde, Renfrewshire, first recorded as "Erskin" in 1225. The etymology of the name is uncertain, but it may be from Celtic elements cognate with the Welsh "ir", green, and "esgyn", to ascend. Henry de Erskyn, who witnessed a confirmation charter by Alexander 11 to the Abbey of Paisley in 1225, is the first recorded namebearer; this notable surname has been borne by the Barons Cardross, and the Earls of Buchan, Kellie, Mar, and Rosslyn. John Erskine, second Earl of Mar of the Erskine line became lord high treasurer of Scotland in 1616. The surname, Sandys, is of Anglo-Saxon origin, and is a topographical name from residence on a patch of sandy soil, deriving from the Olde English pre 7th Century "sand", sand. In the modern idiom the name is spelt: Sand, Sand(e)s and Sandys. William Sandys, knight of the body to Henry V111 (1509), took a leading part in the festivities at the Field of the Cloth of Gold, and was created Baron Sandys of "The Vyne" in 1523. Sir Edwin Sandys, born into a Lancastrian family in 1561, was a founder of Virginia. The first recorded spelling of the family name is shown to be that of William de Sandes, which was dated 1205, in the "Curia Regis Rolls of Surrey", 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.