This is an Olde English locational name which almost certainly originates in the county of Devon. The meaning is 'the dweller in the green valley' from Olde English pre 7th century 'grene slaed', and medieval charters for the county suggest that such a place existed between Tiverton and Exeter. However no such hamlet or site appears in the medieval village list of the Royal Historical Society as updated to 1990. This suggests that the original site may have been literally one farm. Either way the surname has ancient origins and it is probable that as many charters remain unresearched other early surname recordings will be found. Examples of the surname on the registers and church records include Antony Greenslade, in the 1559 Calendar of Proceedings in Chancery for Devon, during the reign of Elizabeth 1st, and Robert Greenslade of Paignton, Devon, a church witness on September 14th 1566. A variant spelling was that of Christopher Grinslade of Chumleigh, Devon, on February 15th 1718. The rolls of the island of Barbados show that a 'Ticquett' was granted by the Secretary to the Governor on October 7th 1679 for one 'Thomas Greenslatt' to travel to 'Antegua'. He was almost certainly originally a 'Greenslade' particularly as there are no other known recordings of 'Greenslatt'. The first recorded spelling of the family name is shown to be that of Robertas de Greneslade, which was dated 1272, the charter 'Testa de Neville' for Devon, during the reign of King Henry 111, known as 'The Frenchman' 1216 - 1272. 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.