Kenstone Hall was a place where injured government intelligence operatives went to recover from their injuries. Patients included agents from UNIT, MI5 and MI6. According to Brigadier Lethbridge-Stewart, its residents were "some of the highest-ranking intelligence operatives" the British government employed.
Some time in the 20th century, the residents and staff of Kenstone Hall were possessed by the Nurazh and the Master. The Third Doctor defeated the Nurazh, and the surviving staff and patients had no recollection of the events. (PROSE: The Touch of the Nurazh)