[1][2] The remains found on the site show that it was originally an Iron Age fort[3] which gave the mount its ancient name, Donnilee.

[4] The hilltop and the surrounding area was "sculpted" to form a motte and bailey fortification with its timber Hall following the Norman conquest.

According to sources it was Thurston De Montfort who built the stone castle here in 1140 during the reign of Henry II,[6] and it remained the De Montfort seat for more than a hundred years.

The Earl of Warwick took possession of the De Montfort's land in approximately 1369, and subsequently the castle's importance declined.

[2] During the early years of the War of the Roses, between York and Lancaster, the castle, which was then unoccupied and had fallen into disrepair, was dismantled, and its heavy timbers were, according to some sources, used for the construction of stately houses at Henley.