This most unusual surname is of Old German and Norman origin, and is one of the variant names derived from a Germanic female personal name composed of the elements "is", ice, and "hild", battle, strife, which was introduced into England by the Normans in the forms "Iseu(l)t" and "Isolde" after the Conquest of 1066. The popularity of the various versions of the legend of Tristan and Isolde led to the widespread use of the given name in the Middle Ages. The other variants of the surname from this source in England include Izzard, Izzett, Izat(t), Is(s)ard, Issett, Issit(t) and Isso(l)t. The personal name is recorded in the Domesday Book of 1086 as "Iseldis" (Dorset), while the surname itself was originally recorded in the late 13th Century. One Robert Isand was listed in 1216, in the "Court Rolls of the Manor of Wakefield" (Yorkshire), and John Isot was recorded in the Poll Tax Records of Yorkshire in 1379. London Church Registers include the following examples of the name: Henen Isat married John Gambyll on October 18th 1551 at St. Stephen's, Coleman Street, while Sara Izatt was christened at St. Andrew's, Holborn, on January 27th 1582. Ann Isatt was christened on September 13th 1760 at St. Mary's, Marylebone Rd,. The first recorded spelling of the family name is shown to be that of Thomas Isolde, which was dated 1275, in the "Hundred Rolls of Suffolk", during the reign of King Edward 1, known as "The Hammer of the Scots", 1272-1307. 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.