Hello misfitz,
There is a bit about this place and family in the book, "Grace and Favour" by Loelia Duchess of Westminster. She was married to Bendor, the nickname for the 2nd Duke of Westminster, and connected to the Cornwallis family I think.
The book seems to be shown as available on internet sites.
The castle has been run as an hotel for many years now. They have a reputation for their medieval banquets.
Jo.