Every superhero needs an origin story. Now Winnie-the-Pooh has one, too.

The estates of AA Milne and his illustrator, EH Shepard, have authorised a prequel exploring the famous bear’s beginnings.

The new book, Winnie-the-Pooh: Once There Was A Bear, will draw on real history.

It will start with the day that Pooh was purchased from Harrods for the infant Christopher Robin, and the first stories in the collection will be set in Mallord Street, Chelsea, where Eeyore and Piglet were among the toys.

Readers will encounter the young Christopher Robin, previously glimpsed in Milne’s poetry collections, When We Were Young and Now We Are Six.

Originally, the little boy named his teddy “Edward”, but he renamed it “Winnie” after Winnipeg, a Canadian black bear that he and his father would often visit at London Zoo.

Jane Riordan, author of the new book, has invented an encounter between Pooh and Winnipeg.

“In the story, Pooh gets a little bit jealous because he thinks there should only be one bear with that name,” she said. “In another story they visit the Natural History Museum, and I used a little bit of creative licence because we don’t know if they did that in real life.

“But we had the idea to see what happens in the ‘before stories’ because there’s quite a lot we know about the real Christopher Robin’s life in London. So we thought it would be really nice to weave that into a prequel.”

The later chapters of the book see the family move to the country and explore the Hundred Acre Wood, where Riordan has included other characters including Rabbit and Owl.

The book will be published in September to mark the 95th anniversary of the release of Milne’s original stories. It will carry illustrations by Mark Burgess, in the style of Shepard’s originals.

Author Jane Riordan and illustrator Mark Burgess worked together on the new book, Winnie-the-Pooh: Once There Was A Bear

Winnie-the-Pooh regularly appears in lists of the nation’s favourite literary characters, and the books are still bestsellers.

Explaining their appeal, Riordan said: “The wonderful thing about Winnie-the-Pooh is that there are no adults. It’s this incredibly free, slightly wild existence and I think that’s something that always resonated with children and perhaps does now more than ever when children have been stuck inside.

“We rarely let them out by themselves, certainly not into woods, so there’s something very freeing about reading these stories. They have a real sense of adventure.”

And the readers are not always children. 

“There is so much in the books that resonates with adults, and they’re actually a bit tricky to read for anyone under the age of six. They’re quite sophisticated, and it’s often adults more than children who love to discover them.”

Trustees of the Milne and Shepard estates were consulted about the stories. 

Riordan said: “The designer tells me that, overall, the trustees were delighted with Mark’s illustrations but they did ask for some small amendments – one being to make Pooh a little stouter.

“They were also very keen for us to feature Piglet’s arrival in the London nursery. I imagined him squeezed through the letterbox, which perhaps explains his small size.”

She has tried to stick as closely as possible to the characters created by Milne.

“It is such a big responsibility, and Milne’s voice is so distinct and beautifully crafted so it was a huge thing to live up to.

“But I think when you’ve read the books as many times as I have, the voices just sort of sit in your head. There were times when I could hear the characters chatting away and I had to say, ‘You need to shush’.”

Anyone wondering if Eeyore’s “before story” will explain the reason for his melancholic demeanour will, however, be disappointed. 

Milne based Eeyore’s character on Christopher Robin’s toy, which is now on display alongside Pooh, Piglet, Kanga and Tigger in New York Public Library.

Riordan added: “The original Eeyore does look pretty droopy and sad, so AA Milne got that spot on.”