This is a good example of a type of toponymic surname found particularly in the southern English counties of Surrey, Hampshire, Kent, Essex and Sussex, where the suffix 'er' was added to some topographical feature, in this instance a 'down' or 'low hill'. The meaning as a surname is 'one who dwells by the down(s)'. The derivation is from the Old English pre 7th century word 'dun', which is of Celtic origin. The marriage is recorded in Canterbury of one William Downer and Barbara Greene in 1683. In the modern idiom the name can be found in other variants, such as 'Downe', 'Downman' and 'Dunman'. The first recorded spelling of the family name is shown to be that of Stephen le Downar. which was dated 1327 Sussex Subsidy Rolls. during the reign of King Edward II 'Edward of Caernafon' 1307-1327. 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.