The 11th Earl of Northumberland, the last Percy earl, died in 1670.
Two years later his widow allowed the keep's materials to be reused to build Chirton Hall.
A total of 272 cart-loads were taken from the keep.
Lord Northumberland's property passed to The 7th Duke of Somerset through marriage.
In 1698, the owners decided not to renovate Warkworth Castle after the estimate to add battlements, floors and new windows came in at £1,600.
Lady Elizabeth Seymour inherited the property from her father in 1750.
Her husband, Hugh Smithson, changed his name to Hugh Percy, and the castle then descended through the Dukes of Northumberland, a dynasty he founded.

During the 18th century the castle was allowed to languish.
The south-west tower was falling apart and around 1752 part of the curtain wall east of the gatehouse was demolished (it was rebuilt towards the end of the century).
The town and its historic ruins were by now attracting interest as a tourist destination, largely due to Bishop Thomas Percy's poem, The Hermit of Warkworth.
In the mid 19th century, The 3rd Duke of Northumberland undertook some preservation work.
His successor, The 4th Duke of Northumberland, contracted Anthony Salvin to restore the keep.
The work undertaken between 1853 and 1858 was not as extensive as Salvin had planned, and was limited to partially refacing the exterior and adding new floors and roofs to two chambers, which became known as the Duke's Chambers, on the second floor.
The Duke occasionally used the chambers for picnics when he visited from Alnwick Castle.
The 4th Duke funded excavations at the castle in the 1850s which uncovered the remains of the collegiate church within the bailey.

In 1922, The 8th Duke of Northumberland granted custodianship of the castle to the Office of Works which had been made accountable for the guardianship of ancient monuments.
The Duke's Chambers remained under the direct control of the Percys.
The Office of Works undertook excavations in the moat in 1924 and removed the custodian from the gatehouse.
English Heritage, who now manage and maintain the site, succeeded as the castle's custodians in 1984, and three years later the Duke's Chambers were given over to their care.
The castle is a Scheduled Ancient Monument, a "nationally important" historic building and archaeological site which has been given protection against unauthorised change.
It is also a Grade I listed building (first listed in 1985) and recognised as an internationally important structure.
The castle continues to be officially owned by the Percy family, currently being owned by His Grace The 12th Duke of Northumberland.
The 11th Earl of Northumberland, the last Percy earl, died in 1670. Two years later his widow allowed the keep's materials to be reused to build Chirton Hall. A total of 272 cart-loads were taken from the keep. Lord Northumberland's property passed to The 7th Duke of Somerset through marriage. In 1698, the owners decided not to renovate Warkworth Castle after the estimate to add battlements, floors and new windows came in at £1,600. Lady Elizabeth Seymour inherited the property from her father in 1750. Her husband, Hugh Smithson, changed his name to Hugh Percy, and the castle then descended through the Dukes of Northumberland, a dynasty he founded.
During the 18th century the castle was allowed to languish. The south-west tower was falling apart and around 1752 part of the curtain wall east of the gatehouse was demolished (it was rebuilt towards the end of the century). The town and its historic ruins were by now attracting interest as a tourist destination, largely due to Bishop Thomas Percy's poem, The Hermit of Warkworth. In the mid 19th century, The 3rd Duke of Northumberland undertook some preservation work. His successor, The 4th Duke of Northumberland, contracted Anthony Salvin to restore the keep. The work undertaken between 1853 and 1858 was not as extensive as Salvin had planned, and was limited to partially refacing the exterior and adding new floors and roofs to two chambers, which became known as the Duke's Chambers, on the second floor. The Duke occasionally used the chambers for picnics when he visited from Alnwick Castle. The 4th Duke funded excavations at the castle in the 1850s which uncovered the remains of the collegiate church within the bailey.
In 1922, The 8th Duke of Northumberland granted custodianship of the castle to the Office of Works which had been made accountable for the guardianship of ancient monuments. The Duke's Chambers remained under the direct control of the Percys. The Office of Works undertook excavations in the moat in 1924 and removed the custodian from the gatehouse. English Heritage, who now manage and maintain the site, succeeded as the castle's custodians in 1984, and three years later the Duke's Chambers were given over to their care. The castle is a Scheduled Ancient Monument, a "nationally important" historic building and archaeological site which has been given protection against unauthorised change. It is also a Grade I listed building (first listed in 1985) and recognised as an internationally important structure. The castle continues to be officially owned by the Percy family, currently being owned by His Grace The 12th Duke of Northumberland.
Warkworth Castle