Royal Council
The Royal Council was the ruling body of Britannia in between the disappearance of Lord British and the ascension of the evil Casca to the throne. They are also sometimes called the High Council, the Britannian Council, or the Ruling Council.
Either way, they were almost all murdered in the Hope for the Future event, as part of the Warriors of Destiny event cycle. Either their remnants, or a successor group (it is not clear which), appointed Casca to the position of "King Pro Tempere" ("Temporary King").