The village is comparatively newer than those around it, as it started out in life as a castle belonging to the lord of the manor of nearby Hanslope. A settlement grew up around the castle of servants and manual workers, and this became the village of Castlethorpe (thorpe being the Old English word for a village). The castle was damaged in 1215 in a feud between Foulkes de Brent, who had been sent by the king, and William Mauduit, the castle's owner. Mauduit was reputedly in rebellion against King John of England. Although Mauduit returned to claim his seat after the king's death the castle was demolished shortly afterward.
The parish church is dedicated to St Simon and St Jude.
Castlethorpe is a village with a population of around 1000 in the Borough of Milton Keynes and ceremonial Buckinghamshire, England, about 3 miles north of Stony Stratford, 4 miles west of Newport Pagnell and 7 miles north of Central Milton Keynes.
It is separated from the county of Northamptonshire by the River Tove.
Castlethorpe has grown up around the church and some traditional old stone cottages at the centre of the village which is currently designated a conservation area.
The manor of Castlethorpe passed as an appendage of Hanslape, from the Mauduits to the Beauchamps and Nevilles, and eventually merged in the crown.
In the parochial chapel of Castlethorpe, Which is an appendage of Hanslape, is a handsome monument in memory of Sir Thomas Tyrrell, above mentioned, who died in 1671.
The parish of Castlethorpe has been inclosed by an act of parliament, passed in 1793, when an allotment of land was assigned to the corporation of Lincoln, as impropriators of the great tithes.