Sebastian Vaughan's father, Lord Vaughan, worked at Lodmoor Research Facility for the Ministry of Defence before being promoted to Cabinet minister. He arranged for Sebastian to join Torchwood Three upon learning of the institute, having originally planned for him to join MI5.
Sebastian did not go home for his father's birthday one year whilst he was in Cardiff. According to Madeline Vaughan, his favourite food was radishes. (AUDIO: The Vigil)