After the death of their first child, Charles and Eleanor Dickinson had another boy, Justin. When he turned eighteen, his mother died of a brain haemorrhage. This prompted him to follow in his father's footsteps and join the military. He soon became a member of UNIT, and was later reported as having been killed in action.
In fact, he had been recruited by the Magnate to be one of their ESPnets. When his father found out he was still alive fifteen years later, he went looking for him and the two were reunited. (PROSE: Instruments of Darkness)