Denton's character is definitely unique - smart, wiley, but really downtrodden. You get the feeling she was disliked, but couldn't understand why, and was constantly trying to fight this opinion people had of her. On one hand she was quite unhinged when she punched Kate in the stomach and battered her neighbour, on the other, she was trying to do the right thing with Tommy Hunter and Carly Kirk (although I think it was the 50k that persuaded her more than anything).
I think it's been really hard for the actors in these role to compete with Keeley Hawes since, although I though Daniel Mays was really good and didn't get a chance to show what he could do in one episode. All the actors in the 'under suspicion' role have been good, really well cast.