Recorded as Greystock, Greystoke, Graistock and Gristock, this is an English locational surname. It originates from the parish of Greystoke or Greystock, in the county of Cumbria and some ten miles from the town of Penrith. The meaning of the name is probably "The place (stoc) of the cray fish." These shellfish were apparently introduced into the local rivers by the Roman garrisons on the famous Hadrians Wall nearby. It is understood that crayfish were plentiful in the area, until about a century ago. Locational surnames are usually "from" names. That is to say surnames given to people after they left their original homesteads to live somewhere else and thereafter were most easily identified by being called after their former homes. Spelling being at best erratic and local dialects very thick, often lead to the creation of "sounds like" spellings. In this case the village is recorded as "Creistock" in 1167, from which the surname descended. It is unclear when the surname was first recorded, but William Graystock appears in the Preston Guild Register of 1539, and Thomas Graistock in the Lancashire Wills record of 1561.