Volstrom

 was the Acting Castellan on Gallifrey.

He tried to make sense of distortions in the Matrix and reported to the High Council about Padrac's matrix projections and Padrac's current mission, mentioning the possibility of a Time War. He presented to the High Council a matrix projection of the destruction of Earth. He was, in reality, working for Ollistra, helping her stop the Doom Coalition's plans.

After Jerastra was killed, Padrac promoted him to Chancellor. He was shot by the Eleven, who was trying to find out where the Eighth Doctor had gone with Ollistra, with a staser modified to allow for regeneration as a means of torture. (AUDIO: Songs of Love)

In quick succession, Volstrom was forced to regenerate at least four times, first to female form, then back to male, and then female again. (AUDIO: The Side of the Angels)