Eregous Bates was a native of Hatre Sedtry in the star system known as Repton's Cluster. (PROSE: Attack of the Cybermen)
He and and Stratton were prisoners of the Neomorph Cybermen in the 27th century who had been partially converted, their limbs replaced by mechanical equivalents. Since full conversion had failed, they were put to work on the surface of Telos.
They escaped and tried to reach Cyber Control, meeting up with Lytton and Griffiths along the way, but Lytton was recaptured and Bates was killed trying to open the door to the time machine. The door opened and a Cyberman shot Stratton and Griffiths. (TV: Attack of the Cybermen)