This name derives from Castle itself a topographical name from the Anglo-Norman French 'castle', meaning castle; fortified building or set of buildings, 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, (The Assize Court Rolls), who owed money to Cambridge Castle. The variant spelling Cassell(e)s is first recorded in London towards the middle of the 17th Century as in Jaques Casselles son of Jaques Cassells and Marie Boutellier who was christened on January 16th 1642 at the French Huguenot Church, Threadneedle Street, London. In Ireland 'Cassells' first appears in the 18th Century. On December 5th 1738 at St. Mary's Cathedral Limerick, a daughter Mary, of William and Catherine Cassells was christened. The first recorded spelling of the family name is shown to be that of Richard Robert Castle, which was dated 1148 - 1154, Select Documents of the Abbey of Bec Sussex, during the reign of King Stephen, 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.