How old are you, and how old is Lady Mary? I'm 29 and Mary is 27. How would you describe Mary? Strong-willed but complex. She has this glacial façade, but underneath it, she's terribly sensitive. The scene in which she's told Matthew is engaged to Lavinia encapsulates her quite well. While there are other people in the room, she shows no feeling, but when it's just her and the maid Anna she bursts into tears. Behind that wall she's built up a tumult of emotion. The thing I love most about Mary is that she is not one of those people who needs to be liked. That confidence is very attractive. Do you have siblings? I'm the baby of three - though I don't think my sisters would want me saying their ages in Radio Times! We don't have any of that rivalry that there is between the Crawley sisters, but I certainly recognise that protectiveness that Mary exhibits towards Sybil as something that my oldest sister has towards me. And her relationship with Edith? Their rivalry has done damage to them both. Edith's decision to reveal the truth about the death of Pamuk continues to have ramifications for the whole household, while Mary' revenge - telling Strallen that Edith felt nothing for him - was horribly cruel. This series, the war has meant there are more important concerns and they've softened to each other a bit, but neither has ever apologised. Do you think Mary deserved what Edith did? No, she didn't, but from what Edith overhears Mary telling Cora - "Why not concentrate on Edith? She needs all the help she can get" - it's no wonder that Edith reacts the way she does. What would she say about Edith's tryst? She'd love that gossip and in some ways find it comforting that Edith got carried away. But I also think that there would be some real sisterhood there and I wonder if Edith would really like to tell Mary. You'd be bursting to tell someone. How has Mary changed over the first two series? Mary isn't quite as vicious as she was. I think she has grown up a lot and she knows she made such a mistake at the end of the first series turning Matthew down. I also think she's very aware of her situation. Mary is in her late 20s and, by the standards of the day, she's on the shelf. Most girls then were married in their early 20s.