Lade Sybil Crawley, later Sybil Branson

Sybil Patricia Branson (née Crawley) (played by Jessica Brown Findlay) is the third daughter of Lord and Lady Grantham, sister of Ladies Mary and Edith Crawley, wife of Tom Branson, and future sister-in-law of Matthew Crawley. Born in 1898. She is fiercely political (devoted to the cause of votes for women) which fuels her desire to break free from the social restrictions of the times. During one episode she wears a daring new outfit which somewhat shocks the family, especially the Dowager Countess. During another episode she, against the will of her father, attends a political husting in the local town in which she gets injured. At one point, she requests cookery lessons from Mrs Patmore and Daisy to help prepare herself for training college in York. In her distress over the news that her friend Tom Ballasis was killed in action, she decides to become an auxiliary nurse with the encouragement of Mrs Crawley and the Dowager Countess. Now called "Nurse Crawley," tends to the sick and wounded soldiers both at Downton and at the nearby village.

After developing a brief crush on her cousin Matthew she develops stronger feelings for Tom Branson, the family's socialist chauffeur. For several months the couple carry out a secretive and muted courtship as they fear their relationship would not be accepted by her family as it went against the social mores of the time. Throughout the series Sybil seems detached from most of the family quarrels about inheritance and this comes to a head when she and Branson reveal their love to her family, with her declaring she doesn't want any money from the estate if it means they have to be apart. By the end of the second series, the couple are heading off to Dublin together having gained Lord Grantham's muted blessing on their engagement and the offer of a small dowry. The pair marry in a small ceremony which is attended by Sybil's sisters. By December 1919, Sybil is pregnant and writes a letter to her mother to inform the residents of Downton - though her mother is excited by the prospect of a grandchild, Robert is still resentful towards his daughter, and admits that he will not visit her. But Cora is working on him to visiting her and letting her visit.