Slyne

 was the Castellan of Gallifrey. He was concerned for Romana II's safety and assigned Lukas to guard her. He didn't particularly like Romana. He noticed that she and Narvin were different to what they were before the assassination attempt. (AUDIO: Emanciptaion)

He called Romana away from a science conference for her to meet Kavil. (AUDIO: Evolution) He later led the expedition to Leela's township to get Lord Zacker back from her. After Narvin played the footage of Zacker's orders to commit murder, he arrested Zacker. (AUDIO: Arbitration)