This uncommon and interesting name has a number of possible origins, each with its own distinct derivation. The most likely source for bearers of the modern surname is the Old Norman French locational name from the place called Guise in Aisne, Picardy, which is first recorded as "Gusia" in the 12th Century, and is of uncertain etymology. This name, introduced into England after the Norman Conquest of 1066, has taken various Anglicized forms, such as Gyse, Cays, Cains, Kees, and Keyse, and is also found in Ireland, where, however, keys(e) may be a "corrupt" form of the Gaelic "O Cathasaigh" (descendant of the watchful one), more commonly found as Casey. The following are the other possible sources of the surname Keyse, also found as Key(e)s, Ke(a)ys, Kay(e)s, and Keeys: an occupational name for a maker of keys or for someone holding the ceremonial office of key-bearer, from the Olde English pre 7th Century "caeg", key; a topographical name for one living or working on a wharf, from the Middle English "kay(e), quay; a patronymic of kay, key, from the Celtic personal name "Cai, Key"; from the Roman "Gains, Cains"; a nickname from the Northern Middle English "kay", jackdaw; or from the Old Scandinavian "kei", left, used as a nickname for a left-handed person. Recordings of the surname in London Church Registers include those of the marriage of Agnes Keyse and John Hopkins, on August 28th 1573, at St. Ounstan's, Stepney, and the christening of Robert Keyse at St. Thomas the Apostle, on August 30th 1641. The first recorded spelling of the family name is shown to be that of William Keys, which was dated 1275, in the "Subsidy Rolls of Worcestershire", 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.