The final Discworld novel written by Sir Terry Pratchett before he died last month at the age of 66 will be released later this year, his publishers have said. The book will be called The Shepherd's Crown and will feature Tiffany Aching, a witch-in-training who has featured in four of Sir Terry's books to date, first appearing in The Wee Free Men in 2003. The novel, which is based in the fictional realm of Discworld - a flat disc balanced on the back of four elephants and a giant turtle roaming through space - will go on sale in September. Scroll down for video . The final book written by Sir Terry Pratchett, The Shepherd's Crown, which will be set in the Discworld universe and feature witch Tiffany Aching, will be released this September, his publishers have said . Tom Weldon, from publishers Penguin Random House, said: 'It is a huge privilege to be publishing Sir Terry Pratchett’s final Discworld novel, The Shepherd’s Crown. 'Terry’s writing is loved and respected the world over and this publication will be an incredibly important and special event for us all at Penguin Random House, and for fans and readers everywhere.' Sir Terry published his fist Discworld novel, The Colour Of Magic, in 1983 and went on to sell 85million books worldwide, with his work being translated into 37 languages. Before that he had been a journalist, writing for the Bucks Free Press, the Western Daily Press and finally the Bath Chronicle. The character of Tiffany, who forms one of several side-plots in the 40 Discoworld novels, first appeared in The Wee Free Men (left) in 2003, and went on to feature in another three books . A Hat Full Of Sky, Wintersmith, and I Shall Wear Midnight saw Tiffany grow to be 16 and become a powerful witch. The plot of the final book is unknown, but the shepherd in the title could refer to her grandmother . He became a press officer for the Central Electricity Generating Board, with responsibility for three nuclear power stations, in 1980. 1948: Born to David and Eileen Pratchett in Beconsfield, Buckinghamshire . 1965: Left school to become a reporter for the Bucks Free Press . 1968: Married wife Lyn. Daughter Rhianna is born eight years later . 1971: Published his first book, The Carpet People, which received good reviews but generated only modest sales . 1980: Left journalism to work in PR for the Central Electricity Generating Board . 1983: Published the first book of the Discworld series, The Colour Of Magic, which sold out during its first day . 1998: Awarded an OBE at Buckingham Palace for 'services to literature' 2007: Diagnosed with rare form of early-onset Alzheimer's after car accident. Becomes a right to die campaigner . 2009: Knighted by the Queen at Buckingham Palace . 2012: He gives an interview stating that, while his health is better than expected, his condition is catching up with him. By this point he is thought to be writing by dictation . 2014: Sir Terry finishes his final book, The Shepherd's Crown, which will be published this September . 2015: Sir Terry dies at his home in Wiltshire. His death is announced by his daughter on Twitter . He was first published in 1971 with novel The Carpet People, but his career as a writer did not truly take off until The Colour of Magic was printed. In total Sir Terry published 70 novels, 40 of which were set in Discworld, blending together elements of fantasy, philosophy and real-world politics, while managing to satirise all three. The character of Tiffany Aching first appeared in 2003. Then aged just nine, she began her training as a witch, and was awarded an imaginary invisible hat to boost her confidence. Over the course of another three books, A Hat Full Of Sky, Wintersmith, and I Shall Wear Midnight, Tiffany turned 16, growing in power and gaining abilities along the way. While the plot of the final Discworld book has not yet been revealed, the shepherd of the book's title could be a reference to Tiffany's grandmother, Sarah Aching, who herded sheep. Sir Terry was born in 1948, the only child of a working-class couple - his father was a mechanic - and brought up in Beaconsfield, Buckinghamshire. Adventurous, and keen on learning by doing, he disliked school and had to be bribed by his parents into reading books. While he eventually became hooked on fiction, that never translated into a love of the classroom and he left as soon as he was able in order to become a reporter. As his literary career took off he won a host of prizes and was handed a total of nine honorary doctorates, before being awarded an OBE in 1998, and was finally knighted in 2009 'for services to literature'. Asked about his success at the time, he said: 'Most writers don’t make much money, they only happen to make some if they’re standing in the station when the gravy train comes in. Sir Terry wrote 70 novels, 40 of which were set in Discworld - a flat planet carried through space on the back of four elephants and a giant turtle - selling 85million copies (pictured after being given an OBE in 1998) 'I thought I was lucky to make some money, then lucky to make a living, then lucky to be a millionaire.' However, in 2007, he was diagnosed with posterior cortical atrophy [PCA], a form of early-onset Alzheimer's. Sir Terry, who was knighted in 2009 (pictured), suffered from a form of early-onset Alzheimer's, and was a right to die campaigner . The first hint that he was not well came as he drove home after watching his father, David, die from pancreatic cancer, when he misjudged a lane and scraped his car along a wall. As he succumbed to the disease he lost everyday skills such as touch-typing, but simply took to dictation software to write his books instead, insisting it made him even more eloquent. He also refused to become self-pitying. He rarely referred to his illness by name, instead preferring to call it 'the embuggerance' He even turned his illness to public campaigning, speaking tirelessly and eloquently in favour of people's the right to die in the manner of their choosing. Sir Terry passed away on March 12 'with his cat sleeping on his bed surrounded by his family' at his home in Wiltshire. His death was announced on Twitter by his daughter, Rhianna, who used his account to write: 'AT LAST, SIR TERRY, WE MUST WALK TOGETHER.' 'Terry took Death's arm and followed him through the doors and on to the black desert under the endless night. The End.' The character of Death, one of the most beloved in the Discworld series, always speaks in capitals. Since Sir Terry's death, mourning fans have donated more than £40,000 to The Research Institute For The Care Of Older People, a charity for which he campaigned.
Sir Terry's final novel, The Shepherd's Crown, to be released in September .
Book finished in 2014, shortly before Sir Terry's death last month aged 66 .
Will star character Tiffany Aching, who first appeared in The Wee Free Men .