Producers of the popular PBS series "Downton Abbey" have confirmed to Fox News that Siobhan Finneran will not be returning as Sarah O'Brien in the next season.

It is not known why exactly Finneran is walking away from the show.

"Downton Abbey" is set in pre world war one Britain and follows the lives of the aristocratic Crawley family and their servants, all living in the huge palace Downton Abbey.

Siobhan Finneran plays troublemaking servant Sarah O'Brien, in a statement to the Mail Finneran said, "I'm not doing any more, O'Brien is a thoroughly despicable human being - that was great to play."

Throughout the show Sarah O'Brien has been involved with countless plots and schemes.

One in particular was causing Cora Crawley to have a miscarriage.

The Mail reports that O'Brien will not be making an appearance in the up coming fourth season but they are "leaving the door open" for her to return.

The "Downton Abbey" cast will be growing for the fourth season with some new and old faces.

Shirley MacLaine will be returning as opera singer Kiri Te Kanawa. New faces include actors Tom Cullen, Nigel Harman, Harriet Walter, Joanna David and Julian Ovenden.

Each new character will add a level of drama to the show. Rebecca Eaton, the Masterpiece executive producer told Fox News "The addition of these characters can only mean more delicious drama, which is what 'Downton Abbey' is all about."