The Great Keys were a power bloc of steadholders within the Great Conclave on the planet Grayson from 1750 PD to 1903 PD that assumed control of the government of the Protectorate of Grayson during the Time of the Great Keys, reducing the Protector to a figurehead.
The primacy of the Great Keys came to an end in 1903 PD with the Mayhew Restoration. (HH2,Companion)