To say that this is an interesting surname is the understatement of the year. We believe that the name is English, and almost certainly locational which is to say that it comes from a "place". Our research indicates that the only absolute "certainties" about the surname is that it is recorded in London in the 18th century as Qualtro and Qualtrough. If "Qualtrough" as a place, did exist we have not been able to establish where it was, and that is unusual What is not unusual, is that at least five thousand British surnames derive from "lost" medieval villages, of which the only surviving memorial is the surname. The place name would seem to originate from the Olde English and Welsh pre 10th century Gwalter, or the son of Walter, similar names being Gwilliam, Gwinn, and Gwatkin, plus "trough", formerly "trog", meaning a channel or bed of a river. A secondary possibility which must not be ignored is that the name is a variant form of something else such as "Quantrill", originally recorded in such spellings as Queintrell and Quayntorell. Before the 20th century local dialects were much "thicker" than now, to the point of being almost foreign languages, whilst spelling was at best erratic, so a change from Quantrall to Qualtrough is not impossible by any means. The earliest examples of recordings that we have are those of Richard Qualtrough, and his wife Elizabeth, at St Botolph's without Aldgate, City of London, on May 10th 1775, and apparently the same couple at the church of Holy Trinity in the Minories, also London, on May 11th 1780, when they were recorded in the spelling of Qualtro.