She’s so efficient that we never get a plotline about her job at Downton. All of Anna’s troubles are personal. I’m immediately thinking about a One. She feels like a small, cheerful dynamo. And she has that moral comfort a One or a Six possesses. She’s not a worrier, though (beyond regular human emotion) as a Six would be. It doesn’t define her.
So, a One.
Nobody in this era is going to jog about the park, but Anna is often shown walking to town. A Body Type would have few other outlets for exercise. She’s physically vibrant and brisk. Also, lol, I think she manages the finances for her marriage (a One trait). Everyone upstairs and downstairs is at ease around her. She has no Envy in her, so she can’t be a Three. Like a Three, though, a One is universally liked and successful. It makes her a useful character to the writers for a terrible rape plotline. No one wants to see Anna harmed, and her physical exuberance is convenient as a pivot point to put her in danger. That’s the dramatic nature of a soap opera, and I can’t complain that the showrunners have integrated Anna’s Enneagram into the story. I just don’t want to watch it.