An autographed manuscript of The Sign Of Four featuring Sherlock Holmes is set to become the most valuable Sir Arthur Conan Doyle item ever offered at auction.

The 1889 manuscript is estimated to sell for 800,000 to 1.2 million dollars (£633,000 to £949,000) as part of an auction held in New York by Sotheby’s during their book week in June.

The British author signed the item twice and it also contains edits to “Americanise” the text prior to publication in the US.

The Sign Of Four
Sotheby’s dubbed The Sign Of Four autographed manuscript an ‘important historical treasure’ (Sotheby’s/PA)

It will be offered alongside a collection of letters between Sir Arthur and JM Stoddart -the editor of Lippincott’s Monthly Magazine in which The Sign Of Four first appeared.

The letters chronicle the book’s progression, including details of deliberations over the title and the author’s happiness with the printing and illustrations.

Richard Austin, Sotheby’s global head of books and manuscripts, said the item was an important historical treasure.

“The autograph manuscript of Sir Arthur’s iconic work, The Sign Of Four, is an exceptionally rare piece of literary history, offering a unique glimpse into his writing process,” he said.

He added that the combined offering of the manuscript and the letters provide “a rich tapestry of insight into the preparation of Holmes for an American audience”.

Sotheby’s is selling the manuscript and letters as part of a larger auction of a collection of literary works from the library of Dr Rodney Swantko.

Swantko, who died in September 2022, was known in literary circles for his extensive collection of over 40 rare books and manuscripts from the past two centuries.

Charles Dickens A Christmas Carol Inscription
Also up for grabs at the auction in New York is a first edition of Charles Dickens’ A Christmas Carol complete with inscription (Sotheby’s/PA)

This included works by Charles Dickens, F Scott Fitzgerald, and Edgar Allan Poe.

Also included in the auction is Sidney Paget’s original drawing for the illustration The Death Of Sherlock Holmes for the short story The Final Problem.

Paget’s version of the detective is the basis of his image in the media today.

Another valuable item set to go under the hammer is a copy of Allan Poe’s Tamerlane And Other Poems from 1827.

It is considered one of the rarest first editions of American literature as only 12 copies are known to exist, only two of which remain in private hands.

It is estimated to sell for between 400,000 to 600,000 dollars (£317,000 to £475,000).

Also on offer is Scott Fitzgerald’s The Great Gatsby, L Frank Baum’s The Wonderful Wizard Of Oz and Dickens’ A Christmas Carol, all first edition presentation copies complete with inscriptions.

The auction will happen in New York from June 11 to 26.