By one account, the court of the Doctor's trial were known as the Three, a trio of High Council members consisting of the Prydonian Goth, the Arcalian Adelphi, and and the Prydonian Socra. The Three had some rule in manipulating the Third Doctor's exile on Earth, with Socra being a secret agent of the Matrix Lords' Celestial Intervention Agency. (PROSE: The Legacy of Gallifrey)
The Three once met at the Station to discuss manipulating Peladon. (PROSE: Legacy)