This interesting surname of English origin is a locational name from Thirlwall in Northumberland, deriving from the Old English pre 7th Century "thyrel" meaning "perforated" plus "wall", "wall". The place is on the Roman Wall which must have had a gap here. The place-name is recorded as Thurlewall in the Assize Rolls of 1256. The surname dates back to the early 13th Century, (see below). Further recordings include one John de Thirlewall (1386), and Rouland de Thirwall (1460) who both appear in the "History or Northumberland". Church recordings include one Eleanor Thirlwall who married John Errington on November 9th 1579, at Hexham, Northumberland, Johanna Thirlewall married Nicholas Robison on November 16th 1586, also at Hexham, and John, son of Roger and Susanna Thirlwall, was christened on July 23rd 1721, at St. Anns, Blackfriars, London. One Connop Thirlwall (1797-1875) was a historian and bishop of St. David's. He is buried in Westminster Abbey in the same grave with Grote. The first recorded spelling of the family name is shown to be that of Richard de Thurlewall, which was dated 1216, History of Northumberland, during the reign of King Henry 111, "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.