Joseph Watkins

Professor Watkins was a scientist and the uncle of Isobel Watkins. After inventing the Cerebration Mentor, he was kidnapped by Tobias Vaughn, who forced him to develop it for use as a weapon against the Cybermen. Watkins was later rescued by UNIT.

Watkins was at least an acquaintance of Edward Travers and his daughter. From them, he learned much about the Second Doctor and the TARDIS. When he finally met the Doctor, his foreknowledge caught the Time Lord by surprise.(TV: The Invasion)

Behind the scenes
Watkins was a last-minute replacement for Travers, who would have made his third appearance in The Invasion had not the relationship between Derrick Sherwin and Travers' creators, Henry Lincoln and Mervyn Haisman not soured.