The Grand Families were the most influential groups in England from the 14th to the 19th century. They were the founders of the Society of St George, and were connected to the Star Chamber.
The Book of the War said that these families were the Cecils, the Greys, the Howards/Arundels, the Percys and the Stanleys, and that each family had adopted the mantle of one of the six ruling Houses of the Homeworld sans House Mirraflex, who would never "do anything as vulgar as forming alliances with the lesser species". However, there was little evidence of intervention on the part of the Houses, and it could have simply been cultural resonance. (PROSE: The Book of the War)