The remains of Hanslope Castle are situated in the village of Castlethorpe, it was probably constructed in the 12th century by William Maudit. There are no traces of masonary on the site but considerable remains of the earthworks of a motte (mound) and bailey type of castle.
The manor of Hanslope was granted by the Conqueror to one Winemar, a Fleming, whose son Walter succeeded, and dying, left his young daughter and the estate to the care of the King, Henry I., who married her to his chamberlain of the royal exchequer, William Mauduit (male doctus). Robert Mauduit, the fourth lord, joined the barons, and, in 1215, held the castle against King John, who set Falk de Brent to besiege and demolish it, which he effected. This was Castlethorpe Castle, near Hanslope, three miles N. of Stony Stratford, in the extreme N. of the county, deriving its name from this ancient castle, which was the seat of the barons of Hanslope. William Mauduit, his son, received back his lands from Henry III., and, in the barons’ war, took part with the King, and attended him in the war. He married Alice, daughter of Gilbert Segrave, and, in 1263, succeeded to the earldom of Warwick in his mother’s right, who was daughter of Waleran de Newburgh, Earl of Warwick. He and his countess were carried off from their castle of Warwick in a raid made on them by de Montford’s garrison at Kenilworth, where they remained prisoners for some time. He died s.p., in 1268, when his sister’s son, William, Lord Beauchamp of Elmsley, became his heir. In 1291 (20 Edward I.) Willielmus de Bello Campo, Comes Warr, received a licence to crenellate the wall round the park below his mansion of Hamslape, which would imply that his house of Hanslope had already been embattled as a castle in place of the demolished castle of Castlethorpe. Upon the attainder of Thomas Beauchamp, Earl of Warwick, this property was granted, in 1397, to Thomas Mowbray, Duke of Norfolk, and, after that nobleman’s attainder, it passed to Edward, Duke of York, who was killed at Agincourt, whereupon his estate reverted to the Crown, and was afterwards granted to various royal personages. Thus it formed part of the portion of the Princess Elizabeth before her elevation to the throne. Charles II. granted Hanslope to the Tyrrels, whose estates were sold to Sarah, Duchess of Marlborough, in 1730, and, being left to her grandson, descended to Earl Spencer. This manor, with that of Castlethorpe, is now the property of Edward Hanslope Watts and Lord Carington.
The castle of Castlethorpe was never rebuilt; its site shoes traces of extensive buildings. The site of Hanslope is now partly occupied by the church ; traces of its deep moat, as well as of some fishponds, can be distinctly seen, and from the castle-hill, which is the site of the ruin of its ancient keep, an extensive view is obtained. (Castles Of England, Sir James D. Mackenzie, 1896)