Cuckney Castle was in the village of Cuckney, Nottinghamshire between Worksop and Market Warsop (grid reference SK566714).
It was a motte and bailey fortress founded by Thomas de Cuckney. It was slighted after The Anarchy in the reign of King Stephen. There are now the low remains of a motte, partly enclosed by a wide ditch and to the west the faint remnants of a bailey.
References
Cuckney Castle Wikipedia(Text) CC BY-SA