She is the niece of Lady Denham, the wife of the late baronet Sir Harry Denham. Her aunt brought her to Sanditon in a matchmaking attempt between Miss Brereton and Sir Harry's heir, Sir Edward Denham. She lived as the companion of Lady Denham while in Sanditon. She is praised quite wholeheartedly by Mr. Parker to Charlotte Heywood. She is a very poor relation of Lady Denham's, and it seems as if the former wealth of the Brereton family must have significantly diminished since Lady Denham's first marriage to the late Mr. Hollis. Either that or Clara is the daughter of a younger son in the Brereton family, and thus that man would not have inherited much if the wealth was entailed.
Clara Brereton is described as being incredibly lovely. Charlotte believes that Mr. Parker's praise of Miss Brereton was completely justified upon meeting the other young lady. Miss Brereton is also elegantly tall, regularly handsome, with a delicate complexion, and lovely blue eyes. She reminded Charlotte of a heroine in the books that Charlotte had borrowed from Mrs. Whitby's lending library.
Charlotte thought it was saddening that such beauty would be in line with such great poverty.