Gregory Lord

 was a protestor of UNIT and worked with Linda Maxwell to do this. He also used Elizabeth Klein as an insider. He was worried when Maxwell was happy with the violence. He became worried after he learnt that Klein told UNIT about his work. When he met the Seventh Doctor, he assumed that the Doctor was an alien who had been kept prisoner by UNIT rather than a willing ally of humanity, and tried to apologise to the Doctor on behalf of the human race and "protect" him from UNIT's attempts to give him orders. On the Doctor's orders he disabled Maxwell's device. Ship made him become violent and use a gun. He was killed by McKenna. (AUDIO: Warlock's Cross)