Jelpax

Jelpax was a Time Lord, and had been at the Time Lord Academy with the Doctor. He was a member of the group known as The Deca.

Unlike many of the others in that group, Jelpax did not become a Renegade Time Lord, instead he remained on Gallifrey becoming a Coordinator of the APC Net. He was a staunch supporter of Lord Cardinal, later Lord President Borusa, his former teacher. (PDA: Divided Loyalties)

Behind the Scenes
It is probable that as a supporter of Borusa he used his access to The Matrix to uncover information about Rassilon and the Game of Rassilon. It may have been Jelpax who discovered the Scrolls of Rassilon for his former teacher. (DW: The Five Doctors)