Recorded in the spellings of Clail, Clayal, Clayill, Clayhill, Clayhills, Cleal, Cleall, Clelle, Cleal, and others, this is an English surname. It is locational and originates from a place called Clayhill or Clay Hill, of which there are or were, at least seven examples in different parts of the country. The one near the city of Bristol, or the one which is now registered as a "lost" medieval village in Devonshire, seem to have provided most nameholders. An estimated seven thousand villages and hamlets have disappeared in England since the 11th century, leaving as their only reminder in many cases, the surname often as with this one, in a variety of spellings. The reasons why villages disappeared is complex, but the usual reasons given are plague, particularly the Black Death of 1348, and "Enclosure" from the 15th century when the commmon lands were seized by landowners, and the tenants driven off. The place name and hence the later surname, derives from the Olde English pre 7th century words "claeg hyll", which are self explanatory. Early examples of the surname recording taken from surviving church registers of the post medieval period include those of Alsopp Cleell, who was christened in the town of Bideford, Devon, on June 18th 1645, and that of Ezekial Clayhill, a christening witness at St Martins in the Field, Westminster, on April 12th 1769. Over the centuries surnames have continued to "develop," often leading to astonishing variants of the original spelling.