Cornbury Park is an estate near Charlbury, Oxfordshire. It comprises about 5000 acres, mostly farmland and woods, including a remnant of the Wychwood Forest.
There are references to Cornbury Park under The parish of Charlbury in the Victoria County History of Oxfordshire. It was a manor near Charlbury held by the Dukes of Marlborough after 1751 and lived in by Charlotte, Duchess of Beaufort (d. 1854). It was an extraparochia area, that is, it was not part of any parish.
For more information, see the EN Wikipedia article Cornbury Park.
Victoria County History of Oxfordshire, volume 10, chapter on Charlbury.