Question: Non-Stop starred the English actress best known for what role in Downton Abbey?
Context: Michelle Suzanne Dockery (born 15 December 1981) is an English actress and singer.  She is most widely known for her performance as Lady Mary Crawley in the ITV (UK) and PBS (U.S.) television period drama series "Downton Abbey" (2010–15), for which she was nominated for three consecutive Emmy Awards in the category for Outstanding Lead Actress In Drama Series, and a Golden Globe Award nomination.  She made her professional stage debut in "His Dark Materials" in 2004.  For her role as Eliza Doolittle in the 2007 London revival of "Pygmalion", she was nominated for the Evening Standard Award. Dame Penelope Alice Wilton, (born 3 June 1946) is an English actress.  She is known for starring opposite Richard Briers in the BBC sitcom "Ever Decreasing Circles" (1984–89); playing Homily in "The Borrowers" (1992) and "The Return of the Borrowers" (1993); and for her role as Isobel Crawley in the ITV drama "Downton Abbey" (2010–15).  She also played the recurring role of Harriet Jones in "Doctor Who" (2005–08). Zoe Boyle is an English actress known for her role as Lavinia Swire on the series "Downton Abbey" and Trinity Ashby on "Sons of Anarchy". Joanne Froggatt (born 23 August 1980) is an English actress of stage, television, and film.  From 2010, she played lady's maid Anna Bates in all six seasons of the period drama "Downton Abbey".  For this role, she received three Primetime Emmy Award nominations for Outstanding Supporting Actress in a Drama Series and won the Golden Globe Award for Best Supporting Actress on Television in 2014. Sue Johnston OBE (born Susan Wright; born 7 December 1943) is an English actress known for playing Sheila Grant in the Channel 4 soap opera "Brookside" (1982–1990), Barbara Royle in the BBC comedy "The Royle Family" (1998–2012), Grace Foley in the BBC drama "Waking the Dead" (2000–2011), Gloria Price in the ITV soap opera "Coronation Street" (2012–2014) and Miss Denker in the ITV drama "Downton Abbey" (2014–2015).  She won the 2000 British Comedy Award for Best TV Comedy Actress and was nominated for the 2000 BAFTA TV Award for Best Comedy Performance for "The Royle Family". Cara Louise Theobold (born 8 January 1990) is an English actress who trained at the Guildhall School of Music and Drama.  Her first acting role was Ivy Stuart in the third and fourth series of television period drama "Downton Abbey" and is also known for voice acting as Tracer in the video game "Overwatch". Non-Stop is a 2014 American mystery action thriller film directed by Jaume Collet-Serra and starring Liam Neeson, Julianne Moore, Michelle Dockery, Lupita Nyong'o, and Scoot McNairy.  An international co-production among France, the United States, and the United Kingdom, it was the first film from Silver Pictures since "Weird Science", and its first film to be distributed by Universal Pictures since the end of Universal's deal with Warner Bros..  The film received mixed to positive reviews from critics and was a box office success. Lesley Nicol (born  1953 in Manchester) is an English actress and three-time SAG Award-winner who is best known for her starring role as Beryl Patmore in the ITV and PBS drama TV series "Downton Abbey". Samantha Bond (born 27 November 1961) is an English actress, best known for her role as Miss Moneypenny in the James Bond films during the Pierce Brosnan years.  She is also known for her role as meddlesome wealthy Lady Rosamund Painswick in "Downton Abbey", spanning from 2010 to 2015, who appeared in a number of episodes including the final episode of the final series.  Bond has also grown prominent from her role as the unreliable Auntie Angela in the BBC comedy "Outnumbered", Bond appeared in the whole show performing in each of the series from 2007 to 2014.  Bond also receives notable mention as the original Ms. Liz Probert in "Rumpole of the Bailey" in 1987. Catherine Steadman is an English actress, best known for playing Mabel Lane Fox in series 5 (2014) of ITV drama "Downton Abbey".  She also played Nurse Angela Wilson in ITV's 1960s drama "Breathless", Joan Bulmer in the final season of "The Tudors" and Maggie Lewis in the 2016 ITV miniseries "Tutankhamun".
Answer: Lady Mary Crawley