Bates and Stratton were prisoners of the 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 Stratton was killed trying to open the door to the time machine. The door opened and a Cyberman shot Bates and Griffiths. (TV: Attack of the Cybermen)
Behind the scenes
In the Attack of the Cybermen novelisation, Bates is given the first name of Eregous and is said to hold the rank of Time Navigator. They are both said to come from the planet Hatre Sedtry in the star system known as Repton's Cluster.