Sir Anthony Strallan is a local landowner and widower after the death of his wife Maud. He was invited to Downton Abbey, as Lady Grantham wished for Lady Mary to marry him. However, as Mary spent a large amount of the evening talking to Matthew Crawley, and later turned down a drive in his car, he became interested in Lady Edith, and she him.
He later returned to Downton to invite Edith to a concert, much to Mary's disbelief. After Edith's announcement that she believed Sir Anthony was going to propose to her at the garden party, Mary made sure to talk to him beforehand, saying that Edith thought an old bore was going to propose to her. Believing that Edith did not love him, he excused himself from the party and a distraught Edith.
The Dowager Countess later invites him to tea with Lady Edith where they discover that Sir Anthony was injured during the First World War and lost use of his arm. Lady Edith says that she would like to pursue a romantic relationship, but Sir Anthony tells her that he is too old for her and to forget him.
He has a sister, Mrs Chetwood.