About 80% of Conan Doyle's lost papers have never been published

The papers and other artefacts include a sketch for the first appearance of Sherlock Holmes in the novel A Study in Scarlet.

The papers - found in a London legal firm's offices - went missing 40 years ago during a dispute over his estate.

The collection, valued at about �2m, will go on display at Christie's auction house in May before being sold.

The collection of 3,000 items also includes personal letters, notes and hand-written manuscripts - 80% of which have never been published.

Opening the dozen or so large cardboard boxes, which had housed the archive since the 1960s, was a spine-tingling moment that I will never forget Tom Lamb, Christie's

It also includes personal effects taken from Conan Doyle's writing desk after his death in 1930.

The sketch of Sherlock Holmes in the novel A Study in Scarlet, with the original title A Tangled Skein crossed through, is expected to fetch up to �150,000.

The collection will go on display at Christie's on 14 May, before being auctioned five days later.

Jane Flower, Christie's manuscript consultant, said the papers were first referred to in a biography of Conan Doyle by John Dickson Carr in 1949.

President's letter

She said: "The whereabouts of this material was previously unknown and it is for this reason that no modern day biography of the author exists.

"Scholars and admirers of Sir Arthur Conan Doyle have long been tantalised by the list of the writer's personal papers published in the authorised biography by John Dickson Carr."

Tom Lamb, the head of Christie's books and manuscripts department, added: "Opening the dozen or so large cardboard boxes, which had housed the archive since the 1960s, was a spine-tingling moment that I will never forget."

The collection also includes letters from his brother and sister, and others received from public figures, including Winston Churchill, Oscar Wilde, Bernard Shaw, PG Wodehouse and the US president Theodore Roosevelt.