We haven’t heard from Pooh Bear in 80 years but, in a move that Eeyore would doubtless expect to end in disappointment, the guardians of A. A. Milne’s estate have sanctioned a third book of ursine adventures.

Return to the Hundred Acre Wood will be published in October and booksellers are already inking it in as a Christmas bestseller.

A. A. Milne wrote only two books about his son, Christopher Robin, and his favourite teddy bear: Winnie-the-Pooh (1926) and The House at Pooh Corner (1928).

In their final adventure together Christopher Robin knighted Pooh (“arise Sir Pooh de Bear, most faithful of all my knights”) before the narrative panned away in a slightly melancholic farewell: “And so they went off together but wherever they go, and whatever happens to them on the way, in that enchanted place at the top of the Forest a little boy and his Bear will always be playing.”

Since then the books have been translated into more than 50 languages and delighted hundreds of millions of readers around the world.

The new project follows the example set by Great Ormond Street Hospital when it asked the children’s author Geraldine McCaughrean to write a sequel to Peter Pan.

Peter Pan in Scarlet sold more than 60,000 copies in hardback over Christmas 2006 and Waterstone’s predicts that a Pooh sequel will do even better.

Sarah Clarke, the bookshop chain’s children’s buying manager, said: “The original Winnie-the-Pooh books outsell Peter Pan six to one. If that extended itself to interest in the new book, we are talking about a monster hit.”

The challenge for David Benedictus and Mark Burgess, the author and illustrator of the new book, is to revive one of the best-loved children’s series of all time in a way that proves sympathetic to the originals without veering into pastiche.

Since 1961 Disney has owned the film, television and merchandising rights to the character of Pooh and created its own spin-off adventures. E. H. Shepard, the Punch staff cartoonist who illustrated the original books, condemned the first Disney film as “a complete travesty”.

Many fans regard the American corporation’s subsequent efforts, which have included the introduction of a gopher character and Christopher Robin’s recent replacement by a girl named Darby, as even less acceptable.

The content of the new book is a closely guarded secret but Mr Benedictus said that it would pick up where The House at Pooh Corner left off, with Christopher Robin returning from school to play with his friends. He refused to say whether the beloved “bear of very little brain” would be joined by new characters.

Michael Brown, for the trustees who manage the affairs of A. A. Milne and E. H. Shepard, said that he had been hoping to give the green light to a sequel for a very long time.

“A lot of people have tried [to write one] including me, but most people only score eight out of ten. You have got to have somebody who scores ten out of ten and David seemed to have the feel and the spirit and the turn of phrase of the originals.”

Two thirds of the profits from the book will go to charity, including the Royal Literary Fund for struggling authors and the Clare Milne Trust, which helps disabled people.

Mr Brown agreed that the stakes were high. “On the one hand you can’t improve on perfection. On the other, if you can offer to the millions of people worldwide who love Pooh another series of stories, isn’t that wonderful? And if it makes money for our charities, isn’t that good, too?”

Benedictus, a veteran writer and producer for television and radio, first came into professional contact with Pooh when he put together an acclaimed audiobook adaptation of The House at Pooh Corner in 1997.

To write the ten stories that make up the new book he tried to immerse himself in Milne’s world, visiting Ashdown Forest, in Kent, where the tales were set and reading everything that Milne wrote for Punch magazine — where he was assistant editor — in the 1920s and 1930s. He said that he found Milne’s concise plotting harder to emulate than his “very educated and slightly jokey” tone.

In addition to his work for Punch, Milne was a prolific writer of plays and novels. He later despaired that the success of the two Pooh books and two books of children’s verse had obliterated his more serious literary achievements.

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