This interesting and unusual name is of French origin and is a topographical surname for a dweller on or near a small river in Brittany in the region of "Ille-et-Vilaine". The river name is "Illet", a tributary of the larger "Ille", which runs through Rennes, and is thought to derive from an ancient Celtic river name meaning trickling stream. Topographical names are some of the earliest names to be created, as topographical features, whether natural or man-made, provided obvious and convenient means of identification. It is likely that this name was introduced by the Hugenot exiles who sought refuge in England, as the name is more numerous in Kent than elsewhere for example, in the christening of William Dilley on the August 7th 1603 at Dartford. The first recorded spelling of the family name is shown to be that of John Dyllie, which was dated July 3rd 1592, at St. Giles, Cripplegate, during the reign of Queen Elizabeth 1, known as "Good Queen Bess", 1558 - 1603. 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.