Epsilon Delta was a Time Lord from a later period than the Seventh Doctor. After working as an attendant to the Gold Usher on Gallifrey, having to constantly bow to other Time Lords, with just mundane duties and no true responsibility, he began nursing a lot of anger towards his own people, and later he began to wish for revenge against the Time Lords for not taking him seriously.
He took advantage of the spare time his job provided to work in the workshops to create androids, and he also read information from the archives. No-one expected him to know how to prime a TARDIS, but he did. He also worked on building androids since no-one paid him much attention, and he placed them inside the TARDIS he primed.
After having become bored and feeling his intellect being wasted on Gallifrey, he took the Type 102 TARDIS and escaped to Earth. He found his TARDIS's voice-activated lock and reliable chameleon circuit to be his ship's best features. There, he faked credentials to become the President of St Matthew's College. Inspired by other renegades from an earlier epoch such as the Rani, the Master, and the Doctor especially, he took the title of "the President" as he enjoyed it.
He was an enthusiast of wine and fine foods and was particularly adept at electronics and cybernetics, for which he received a double beta in. He created several black androids and the assassin Amanda, all of whom were shapeshifters. He also believed very highly in himself. He later made contact with the Garvond and entered into an alliance with it until the Garvond no longer needed him. He visited several planets, including the Leisure Hive of Argolis before he died after meeting Sontarans, and he had already regenerated into his second incarnation by the time of his death as a result of the encounter.
He wasn't fond of his second incarnation's appearance, despite Time Lords not meant to care what they looked like since they would regenerate into different incarnations anyway, but he had learnt external appearances were important in some parts of the universe. Despite his views towards his second body, Epsilon Delta was quite vain and he wanted respect from everyone. (PROSE: The Dimension Riders)