This interesting name is of Medieval English origin and is locational from places so called in Berkshire, Northumberland and Warwickshire, first recorded in the Domesday Book of 1086 as 'Grenuedone' (Berkshire), 'Grendone (Northumberland)' and 'Grendone (Warwickshire)', and deriving from the Old English elements 'grene', green and 'dun', a hill. However, the placenames in Herefordshire, Grendon Bishop and Warren, are recorded in the Domesday Book as 'Grenedene', and derives from 'grene', green and 'denu', a valley. During the Middle Ages, when people migrated from their birthplace to seek work elsewhere, they would often adopt the placename as a means of identification. In Baginton, Warwickshire, on December 7th 1725, one Ann Grendon was christened. The first recorded spelling of the family name is shown to be that of Christopher Grendon, marriage to Annes Sheyll, which was dated July 11th 1573, Much Marcle, Herefordshire, during the reign of Queen Elizabeth 1, 'Good Queen Bess', 1558-1603. 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.