Maria Brontë - mother of the authors Charlotte, Anne and Emily Brontë, and their three siblings - died when her children were very young.
Among the few possessions she left behind was the book "The Remains of Henry Kirke White" by Robert Southey, and according to the Brontë Society, the book was "very valuable" for the family.
Family members have not only left notes and sketches in the book - among the pages was also previously unpublished material in the form of a short story and a poem written by a teenage Charlotte Brontë.
"We knew the book existed, but we did not know that these papers were in them," the Brontë Society spokeswoman Rebecca Yorke told The Guardian.
- They have never been published or appeared before.
Contains public flogging
The script is dated to 1833, when Charlotte Brontë was seventeen years old.
Both works are to be connected to the fantasy world Angria, which Charlotte and her brother Branwell fantasized together and about which they wrote several stories together.
The short story will contain, among other things, a public flogging and a caricature of a religious opponent of the Brontë children's father.
The poem is about Marcy Percy, wife of the King of Angria.
Ann Dinsdale, who works at The Brontë Parsonage Museum, calls the book with its contents "one of the most important Brontë objects that has emerged in many years."
Nice start to the 200th anniversary
Charlotte Brontë was born in 1816 and next year the Brontë Society is planning a major two hundredth anniversary.
The Brontë Parsonage Museum in Hayworth, located in the house where the Brontë sisters once lived, sees that the book and especially the new manuscripts will be a welcome addition and highlight to their exhibition.
This week has been a real highlight for those interested in 19th-century British literature: earlier this week, a 20-page pamphlet was found by author and poet Percy Shelley, who has previously been thought to have been lost, writes the BBC.