A story by children's author Beatrix Potter, written more than a century ago, is to be published for the first time after the rediscovery of the tale which features some of her best-known characters such as Peter Rabbit."The Tale of Kitty-in-Boots", penned by Potter in 1914, was found by publisher Jo Hanks after she came across an out-of-print biography of the author from the 1970s which referred to the story in a letter Potter had sent to her then-publisher and an unedited manuscript. Hanks then discovered three handwritten manuscripts in children's school notebooks which were in the archive of London's Victoria and Albert Museum along with a rough colour sketch of Kitty-in-Boots. "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."Most excitingly, our treasured, mischievous Peter Rabbit makes an appearance - albeit older, slower and portlier."Penguin Random House are to publish the new story in September with drawings provided by Quentin Blake, one of Britain's most renowned illustrators. "Once upon a time there was a serious, well-behaved young black cat," the book starts, according to an extract on the Penguin website."It belonged to a kind old lady who assured me that no other cat could compare with Kitty. She lived in constant fear that Kitty might be stolen - 'I hear there is a shocking fashion for black cat-skin muffs; wherever is Kitty gone to? Kitty! Kitty!'" Hanks said Potter intended to publish the tale but marriage, the outbreak of World War One and her concentration on her farming business had got in the way.Potter, born 150 years ago, remains one of the world's most popular children's authors. Two million copies of her "little books" are sold globally every year and more than 45 million copies of "The Tale of Peter Rabbit" have been sold since it was first published in 1902. "She was a wonderful story-teller. There's nothing like it, tell a good story, tell it clearly, tell it well and you've got an audience," actress Patricia Routledge, patron of the Beatrix Potter Society, told BBC Radio. "She was very scientific about her approach to animals. She was a bunny-boiler. She and her brother boiled a bunny to find out what the structure was like."