Laura Carmichael has admitted her secret daughter storyline in Downton Abbey has been "hard going".

In the new series of the ITV period drama, the actress's alter-ego Lady Edith Crawley has to keep her daughter a secret from her family to avoid a scandal, while all the time the child is living nearby.

Laura told the RadioTimes.com that it hasn't always been easy to shoot.

She said: "It did feel different this year.

"It was quite hard going, just because of the nature of it. It's very secretive and it's far more serious a story line than I've played before, but still just having a dreamy time shooting it.

"[It's] a great juicy storyline to get into - it's been a real treat."

Laura continued: "[It's a] kind of tragic scenario of being close and yet far from her daughter and living with that secret. Living with the pain of that whilst not being able to confide in anyone else - and Mr Drew, the unlikely confidant, the farmer down the road, being the only one who really knows how painful it is for her.

"He could at any point expose them and ruin them and bring shame on them and yet doesn't because he has this loyalty to this family.

"It's an interesting year."

Downton Abbey returns on Sunday September 21.