The Telphin were a race who banished war from their culture, becoming peaceful lovers of art and masters of psycho-sculpture.
One day, the Chaktra, a war-like race, were in orbit around the planet. They received a garbled report and misunderstood it, believing that the Telphin were now allied with their enemy. They bombarded the planet and wiped out the Telphin in that single day.
On that same day in 1995, the Doctor was telling Simon the story of the Telphin, to try and prove that war was evil. As he did so, Simon began to remember the day when he had met the Doctor in '45. At that moment he was filled with light and the spirit of the Telphin was freed from him. It then left Earth to rebuilt the Telphin civilisation. (COMIC: Memorial)