Sybil Branson

The former rebel of the family, and wife of Tom Branson, Lady Sybil Patricia Branson (nee Crawley) (b. August/September - December 1895 - d. August/September 1920) was the youngest daughter of Cora Crawley, Countess of Grantham and Robert Crawley, 5th Earl of Grantham, sister of Lady Mary Crawley and Lady Edith Crawley, sister-in-law and fourth cousin to Matthew Crawley, mother to Sybil (Sybbie) Branson, niece of Rosamund Painswick and Marmaduke Painswick, granddaughter of Martha Levinson and Isidore Levinson and Violet Crawley, Dowager Countess of Grantham and the 4th Earl of Grantham, great-niece of Roberta and Mr Gordon, first cousin-once-removed of Susan MacClare, Marchioness of Flintshire, first cousin-once-removed-in-law of Hugh MacClare, Marquess of Flintshire and second cousin of Lady Rose MacClare.

Season Three
Sybil writes Mary to say that she and Tom do not have the money to come to Mary's wedding. Later the money is sent to them. When Sybil arrives she tells a confused Robert that she hopes he was the one who sent it, but Robert informs her that he did not. Though Robert suspects that Isobel sent the money, it is Violet who finally admits to it.

Everyone comments about Tom not having appropriate suits for dinner and for the wedding, and Sybil says that they can use the money to buy these, but Tom refuses. Sybil asks him to not bring up the Irish Republican cause and warns him that a former suitor, Larry Grey will be at dinner the following evening. Sybil is distraught and pleads with Tom, when he behaves in a drunken and argumentative manner at dinner, but it turns out that he was drugged by Grey and all is well.

Sybil introduces Tom to her grandmother Martha Levinson who seems confused about what a journalist is. Mary is married with Sybil in attendance and Tom as Matthew's best man. They return afterward to Dublin.

Tom must leave Ireland hurriedly, leaving a pregnant Sybil to close up the house and follow him the next day. Sybil has called and left a cryptic message with Edith that she is well and that they didn't try to stop her. Tom explains to Robert and Cora that that he is wanted by the police for taking part in the meetings and activities of the Irish revolutionaries, and Robert lambasts him for leaving a pregnant Sybil to travel alone.