Featuring an older Peter Rabbit, ‘The Tale of Kitty-In-Boots’, was rediscovered two years ago by Jo Hanks, a publisher at Penguin Random House Children's, after finding reference to the work in a biography on Potter.
Following this discovery, three manuscripts were then tracked down in the Victoria and Albert Museum (V&A) in London. The story was found handwritten in school notebooks, complete with a rough colour sketch of Kitty-in-Boots, a pencil sketch of the notorious villain Mr Tod. Additionally, some of the manuscript was laid out in a dummy book.
Hanks, said: "The tale really is the best of Beatrix Potter. It has double identities, colourful villains and a number of favourite characters from other tales (including Mr. Tod, Mrs. Tiggy-Winkle, Ribby and Tabitha Twitchit).
"And, most excitingly, our treasured, mischievous Peter Rabbit makes an appearance - albeit older, slower and portlier!"
Illustrator Quentin Blake – known for his work with author Roald Dahl – is to illustrate the book.
Blake said: "It seemed almost incredible when, early in 2015, I was sent the manuscript of a story by Beatrix Potter; one which had lain unpublished for 100 years and which, with the exception of a single drawing, she had never illustrated.
"I liked the story immediately - it's full of incident and mischief and character -and I was fascinated to think that I was being asked to draw pictures for it.
"I have a strange feeling that it might have been waiting for me."
According to the V&A archives, Potter intended to finish the story, but major life events, including the First World War, marriage, farming work and illness meant she never returned to finish the tale.