Recorded in several forms including Whitmarsh, Whitemarsh, Whitmesh and Whitmas, this is an English surname. It is locational from what now appears to be a "lost" hamlet in the parish of Sedgehill, in the county of Wiltshire. The derivation is from the pre 7h century Olde English "hwit" meaning white, or more likely either chalky or perhaps phospherous, and "mersc", a marsh or water wasteland. As much of Britain was an undrained morass at this time, it is perhaps surprising that there were not more places so called, or that the surname was not more popular. What is certain is that this is a "from" name. That is to say a surname that was given to people after they left Whitmarsh and moved elsewhere. It is likely that the village largely disappeared as a result of the infamous Enclosure Acts of the mainly 17th century. These acts legally enabled the land owners to fence and drain the common lands, usually forcing the existing tenants to leave. Spelling being at best rudimentary and local dialects very thick, soon lead to the development of "sounds like" spellings. Examples of this surname recorded in early surviving registers of the diocese of Greater London include Edward Whitmesh, a witness at the famous church of St Martins in the Field, Westminster, on January 21st 1684, John Whitmarsh, the son of Nicholas Whitmarsh, christened at St Dunstans in the East, Stepney, on July 6th 1696, and Sarah Whitemarsh who married John Catt at St Pancras Old Church, in the city of London, on November 2nd 1760.