Due to his ineffective administration, several members of the colony formed a rebel group, which was secretly led by the head of security, Bragen. He supported Lesterson's experiments on the Daleks, believing that they could be used to serve the colony and help improve it.
When Hensell left to inspect the mining operations on perimeter, he left Bragen in command. When Hensell returned, he found out Bragen had taken over the colony. After Hensell refused Bragen's offer to help him, Bragen had a Dalek exterminate him. (TV: The Power of the Daleks)