William I awarded granted the land around Reigate to one of his supporters, William de Warenne, on whom he also bestowed the title Earl of Surrey in 1088.
It is believed that his son, William De Warenne II, ordered that Reigate Castle be built, though the de Warennes had their base in Lewes, Sussex. Around 1150 the de Warennes ordered that a town was constructed below the castle. The new town, Reigate, replaced a nearby settlement known as Cherchefelle.
It is believed that the name came from Roe-deer Gate, as the town was situated near to the entrance to the de Warenne's deer park, which is now Priory Park and Reigate Park. It is reputed that prior to the signing of the Magna Carta, the rebellious barons met in conference to hammer out the details of the document in the caves. It later fell into decay and was demolished in 1648.
During the 13th century the Reigate Priory was founded for regular Canons of the Order of St Augustine. After the dissolution of the monasteries in 1535 the estate was granted by Henry VIII to Lord Howard of Effingham who converted the Priory into a residence. The Howard family, including the Lord High Admiral who commanded the force which defeated the Spanish Armada, lived there for about 140 years. The building is now used as a school.History