Lady Agatha, born at Duneagle, is the elder sister of Hugh MacClare, Marquess of Flintshire[1], the younger sister of Lady Louisa, the sister-in-law of Susan MacClare, Marchioness of Flintshire, the granddaughter of the Countess of Newtonmore, the aunt of James MacClare, Lord Newtonmore, Lady Annabelle and Rose and the aunt-in-law of Lady Annabelle's Husband.

In Autumn 1920, Violet Crawley informed Rose that she would go up to Duneagle Castle and spend the rest of her vacation with Agatha; this information horrified Rose, who threatened to run away. Violet managed to rein Rose in by saying that until she was older, she was under their command. Rose later claimed that Agatha was "a monster"[2]. In 1920, Agatha was residing at Duneagle Castle but she was only there to care for Rose, and had left by September 1921.



“ I know. Lady Agatha isn't much of a party person, I admit. ”
Violet Crawley, Dowager Countess of Grantham.[来源]
“ I'm being sent North tomorrow with a monster for a jailer! ”
—Rose on Agatha at the Cricket Match.[来源]
“ Alone in Scotland with Aunt Agatha!? ”
—Rose's horror at being sent to Duneagle under the watchful eye of her aunt.[来源]
“ It was nursery game: Louisa was a lobster, Agatha was a shark - which is easy to believe - and I suppose Shrimpie was a shrimp. ”
—Robert on Louisa, Agatha and Shrimpie.[来源]


Agatha's surname may be MacClare, for we do not know if she has ever been married. Her current whereabouts are unknown.
  1. Robert confirms this in the 2012 Christmas Special
  2. Episode 3.08