This interesting surname is of Medieval English origin and is a dialectal variant of a locational name Ilsley from a place so called in Berkshire. The earliest recording of this place name is in the Domesday Book of 1086 and appears as 'Hildeslei', and in the Pipe Rolls of 1130 as 'Illeslai', deriving from a personal name 'Hild' with the Old English pre 7th Century 'leah', a grove, or clearing. This surname is well recorded in Berkshire, along with other variants, which illustrate the name development, for example, Marryan Eelsleye (1565 Burghfield, Berkshire), Matthewe Yllesly (1566, Bradfield, Berkshire), Jone Elsley was christened on June 20th 1596 and Lucy Elsely married William Burrows on October 1642, both at St. Dunstan's, Stepney. The first recorded spelling of the family name is shown to be that of Thomas Elsley, marriage to Alice Hornby, which was dated March 10th 1557, Pangbourne, Berkshire, during the reign of Queen Mary, 'Bloody Mary', 1553-1558. 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.