This interesting and unusual surname is of Anglo-Saxon origin, and is locational from a place so called in Lincolnshire. The name is derived from the Olde English pre 7th Century "caester, ceaster", a Roman camp or fort. Locational surnames, such as this, were usually acquired by a local landowner, or by the lord of the manor, and especially by those former inhabitants of a place who had moved to another area, usually in search of work, and were thereafter best identified by the name of their birthplace. The placename was first recorded as "Castre" in the Domesday Book of 1086. The surname could also be a variant of Caister, which is locational from two places so called in Norfolk. The modern surname can be found as Caistor, Caister, Castor and Caster. Among the Recordings from Lincolnshire Church Registers include: the marriage of Robert Caistor and Ann Shaw on February 2nd 1675, at Belton, in Axholme, and the marriage of Thomas Caistor and Elizabeth Maw on April 28th 1762, at Doddington. The first recorded spelling of the family name is shown to be that of Christopher Caster, which was dated 1540, christened at Field Dalling, Norfolk, during the reign of King Henry V111, known as "Good King Hal", 1509 - 1547. 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.