Colony in Space was written by Malcolm Hulke, and various aspects of the story are full of Hulke's hallmark characterizations. Most prominent are The Doctor in the role of peacemaker, and a conflict featuring two (or three) different factions, none of which are necessarily good or evil, but have elements of each within their numbers.
The Colonists all have a common goal - staying on the planet (despite some of them wishing to leave earlier) and forcing IMC off their patch. Ashe, the leader, wants to go about this through the proper legal avenues; Winton wants to resort to more clandestine methods, mostly involving force. IMC has three main cogs - Dent, Morgan, and Caldwell. Morgan is the most sadistic of them all in wanting the miners to clear off, freely using lethal force to do so. Caldwell is the opposite of Morgan. He's just a miner, and wants to do his job without anyone getting hurt, and that means, in his eyes, that the colonists should leave for their own safety. Dent could be construed as being in the middle of Morgan and Caldwell, but it is he who authorizes Morgan's actions, however discreetly. However, Dent is as dedicated to his job (getting as much profit for IMC as possible) as both Morgan and Caldwell are to theirs. Dent is just doing his duty without any beastliness or discrimination. And that makes him the most terrifying kind of villain of them all.
On another topic, doesn't Helen Worth have the goofiest smile you've ever seen?