Borusa's regeneration (Arc of Infinity)

Following the Sontaran invasion of Gallifrey, Lord Chancellor Borusa (TV: The Invasion of Time ^[+]Loading...["The Invasion of Time (TV story)"]) regenerated into a new incarnation who was Lord President by the time of the Second Omega Crisis. (TV: Arc of Infinity ^[+]Loading...["Arc of Infinity (TV story)"])