Recorded in many forsm as shown below, this is an English surname but of French pre 7th century origins. It derives from the word 'castle' itself a topographical name meaning a fortified building, and especially the residence of a feudal Lord. The name may also have denoted a servant who lived and worked at such a place. Occasionally it referred to a tenant paying rent to the castle as in Henry de Castell, circa 1260, in the Assize Court rolls. He owed rent money to Cambridge Castle. The spelling as Cassel, Cassels, Cassell, Cassells is recorded in the church registers of the city of London as in that of Jaques Casselles, the son of Jaques Cassells and Marie Boutellier who was christened on January 16th 1642 at the French Huguenot Church, Threadneedle Street. In Ireland the name is first recorded about a century later, and example being that of Mary Cassels, on December 5th 1738 when she was christened at St. Mary's Cathedral Limerick. The first recorded spelling of the family name is shown to be that of Richard Castle. This was dated 1148 in the Select Documents of the abbey of Bec in the county of Sussex, during the reign of King Stephen, also known as the Count of Blois, 1135 - 1154. 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.