Now I have no idea if Philip Glenister will be playing the hero in Cranford, (Simon Woods who plays Dr Harrison is a candidate as is Alisitar Petrie who plays Major Gordon) but I bet he will stealing scenes just as he did in Life on Mars where he played DCI Gene Hunt.
Both Gene Hunt and John Thornton are alpha personalities. Both like the leadership roles they have but they approach them in different ways.
Gene Hunt in that tv series is ultimately a 8. He cares about people once they become his. He is the King of the Jungle on his patch and he looks after people. He has a disregard for rules, because his main purpose to protect his team. He enjoys the challenge and wants to determine the course of his life. He is tough, but he has integrity. He dominates the screen. Protect and defend are really his watch words. He goes along with the status quo if it suits his purpose.
John Thornton on the other hand is very much more a 6. He likes to follow rules. Either rules he has made for himself or rules society has made. He cares about his factory, but he demands his workers follow rules. He is a hard man but he is honest. He is searching for security for himself and to a certain extent for his workers. You see this in the way he refuses to risk the factory on a speculative gamble. It is only after he loses that security that he is able to break some of the rigid rules -- most importantly being able to take the risk and confess his love.
I suspect Richard Armitage is a team player -- someone who learns his lines, gets on with it and is fairly punctual. If not, he knows why he is breaking the rules. In short he tends to play people who know the rules and are more comfortable with authority. He strikes me as being more comfortable playing characters who are in the 6 range.
I suspect that Philip Glenister, although disciplined, enjoys stealing scenes. I suspect he will improvise if it is going to make a better scene. I think he feels very strongly about the shows he is in and is not adverse to speaking his mind when the authority might differ. In short, from what I have seen of his work, he strikes me as being far more of an 8.
I could be completely wrong this but hopefully, it sort of demonstrates the differences between 6 and 8.