The earliest surviving Jane Austen manuscript, a heavily corrected draft of the unfinished novel The Watsons, is expected to fetch up to £300,000 when it is auctioned in July.
The historic draft of The Watsons, billed as the most important Austen item to come to the market in 20 years, comes with an estimate of £200,000 to £300,000.
The writer is thought to have penned the work in 1804 and the heavily-corrected script is said to be the earliest surviving manuscript for an Austen novel.
Her incomplete draft of the work, which was not published during the novelist's lifetime, will be sold at the auctioneer's English literature and history sale in London on July 14.
None of the manuscripts of Austen's completed novels survives, except for two draft chapters of Persuasion, her early work Lady Susan and the fragment Sanditon.
Gabriel Heaton, Sotheby's senior specialist in the auctioneer's books and manuscripts department, said: "This unique manuscript provides scholars with important evidence, not just of how Jane Austen composed and revised her work, but also of how her other manuscripts must have looked before they were edited by her publishers.
"Austen's characteristically nuanced texts were the result of careful reworking and here we can actually see her in the process of rethinking and adjusting her work.
"The Watsons is quintessential Jane Austen in style and the influence of this novel on her later works can be clearly seen."
The story centres on a family of four sisters - the daughters of a widowed clergyman - and contains many of Austen's running themes and shrewd social observation.