Peter Rabbit is back, in a previously unpublished story by English children's author Beatrix Potter.

The Tale of Kitty-In-Boots was tracked down by publisher Jo Hanks after she found a reference to the manuscript in an out-of-print book about the author from the 1970s. Potter had written to her publisher about the story of "a well-behaved prim black Kitty cat, who leads rather a double life."

The feline tale also features an older version of Peter Rabbit, the best-known creation of Potter, who died in 1943.

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Hanks discovered manuscripts of the story as well as one rough colour sketch of Kitty-in-Boots and a rough pencil drawing of the villain Mr. Tod in the Victoria & Albert Museum's Potter archive.

She also found letters that revealed Potter had intended to finish the story, but "interruptions" — from the start of the First World War to farm work to illness to her marriage — eventually got in the way and she never returned to the tale.

"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)," Hanks said in a statement.

I liked the story immediately — it's full of incident and mischief and character... I have a strange feeling that it might have been waiting for me. - Quentin Blake

"Most excitingly, our treasured, mischievous Peter Rabbit makes an appearance — albeit older, slower and portlier!"

Generations of children have grown up with Potter's tales of animal characters including Peter Rabbit, Jemima Puddle-Duck and hedgehog Mrs. Tiggy-Winkle.

Quentin Blake, best known for his work with beloved children's author Roald Dahl, will provide illustrations.

British children's author Beatrix Potter had written to her publisher about the story of 'a well-behaved prim black Kitty cat, who leads rather a double life.' (Express Newspapers/Getty Images)

"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almost incredible when, early in 2015, I was sent the manuscript of a story by Beatrix Potter; one which had lain unpublished for a hundred years and which, with the exception of a single drawing, she had never illustrated," Blake said.

"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."

Penguin Random House will publish the tale in September. This year marks the 150th anniversary of Potter's birth.