Michelle Dockery, who plays eldest daughter Mary in Downton Abbey, reveals there are surprises in store as the ITV1 series reaches its climax on Sunday…

The big news this week is that Cora is pregnant! That could change everything for Mary, couldn’t it?
“Oh yes, it throws a real spanner in the works!”

If the baby is a boy, it will be heir to Downton. Does that change Mary’s thoughts about Matthew’s marriage proposal last week?
“Her aunt Rosamund [Samantha Bond] cautions her not to answer immediately, and Mary listens because she adores her aunt, who is outspoken and modern. Mary and Matthew have a very interesting relationship. There are certainly sparks between them and her affections towards Matthew have grown throughout the series. Deep down, Mary is very attracted to him, but she’s too stubborn to admit it. I think they’re a good match, but it’s complicated. Mary wants to marry because it feels right, not because she’s being set up.”

Also this week, Mary discovers her sister, Edith, started the rumours ruining her reputation. Why do they dislike each other so much?
“Mary and Edith have a really catty relationship. They’re really close in age and there’s a lot of competition between them. Mary feels it’s her absolute birthright to inherit the estate and Edith resents that.”

But why did Edith take it so far and reveal Mary’s tryst with Pamuk?
“I think Edith feels Mary gets all the attention and she’s always in her shadow. They’re constantly trying to outdo each other and so there are some incredibly bitchy moments between them.”

What events during the series have had the most effect on Mary?
“Her experience with Pamuk really changed her. She’s grown up quite quickly.”

Why do you think the programme has become so popular?
“I think it’s because the characters have been written so brilliantly by Julian Fellowes. Everyone gets their own little story, so it changes a lot between each episode. There are some real surprises to come and I think the audience will be intrigued to see how things are picked up in the second season!”