Tom and Lady Sybil Branson.
The Branson Family are a working class Irish Catholic family who are spread throughout Ireland and Great Britain. However, they may not be entirely poor, since one of Tom Branson's grandfathers was a tenant farmer in the county of Galway, specializing in sheep. Tom himself seems to have spent most of his life in the city of Dublin, telling Matthew Crawley he isn't much of a country boy.
Mrs. Branson, who lives in Dublin, has at least two children: Kieran and Tom. Both have worked with cars, Kieran being a car mechanic based in Liverpool, and Tom having worked as a chauffeur in both Ireland and England.
Tom mentions having more than one cousin, indicating his mother and/or his father may have at least one sibling. A male cousin was murdered by an English officer during the Easter Rising, "because he was probably a rebel." It is likely then that the majority of the family hate the English. Tom later hints at having at least one female cousin in Ireland.
Tom is well-read, interesed in history, and has strong socialist and republican political views. After being hired as chauffeur to the Earl of Grantham, he becomes very drawn to the earl's youngest daughter, Lady Sybil Crawley, a woman likewise politically minded and caring for the less fortunate.
Despite his love for Ireland and his opposition of the English and nobility, Tom falls in love with Sybil and remains in England for years before she agrees to marry him against her father's wishes. They marry in 1919. They live in Dublin for roughly a year until in 1920 they are forced into exile in England after Tom is suspected of being involved in the torching of an Irish noble's estate. He is devastated, but remains at Downton Abbey, eventually being hired as the estate's agent.
Lady Sybil dies soon after giving birth to a daughter. Tom names the baby Sybil, after her mother, but she is commonly referred to as Sybbie. She is baptized Catholic in Ripon, attended by Kieran and her maternal family.
Notes
- It is unknown if Tom's father is still alive, as well as how many cousins and siblings he has. It is known, however, that his mother and at least one brother are alive and that he did, at one point, meet one of his grandfathers who was a sheep farmer.