The news that Sarah Odedina is to leave Bloomsbury Children's Books after 14 years came as a shock on Monday, as London publishing was winding down for the summer. Odedina, who has published all of the Harry Potter titles, will take the reins as managing director and publisher of a to-be-named children’s fiction list at Bonnier, the privately owned Swedish media group whose U.K. operation already includes the illustrated children’s publishers Templar and Autumn. Odedina’s start date has not yet been announced and she has agreed to stay on at Bloomsbury until a successor has been named.

“It was a very hard decision to leave Bloomsbury but a very easy decision to join Bonnier,” Odedina told PW this afternoon. “These opportunities don’t come along very often and it was so clear that I should accept it. It’s very, very exciting. I’ve had 14-and-a-half really wonderful years with a creative, entrepreneurial, original company and I’ll be sorry to leave my colleagues and my authors.” During that time, she has of course been part of “an extraordinary piece of publishing history,” an experience neither she nor anyone else is likely to replicate, at least in our lifetime.

Besides J.K. Rowling, whom she called “a very talented author” she hopes will favor her with any future projects, Odedina published Carnegie Medalists Sharon Creech, Jennifer Donnelly, and Neil Gaiman, as well as Louis Sachar, Debi Gliori, Celia Rees, and Graham Marks.

Speaking to PW, Richard Johnson, CEO of Bonnier Publishing, said that the nascent imprint had been six months in the planning, the idea 18 months in the making and an acquisition was considered. But with nothing appropriate in the offing, the decision was made to go it alone. “We wanted to do it properly and we weren’t going to do it at all unless we were able to appoint a top person to the job, which we’ve done with Sarah. We talked to lots of people. We’ve got big ambitions.”

Johnson wouldn’t be drawn on his comment, made in the official statement, that “Bonnier is committed to grow in the English language.” When asked if that meant expanding into the U.S. he said “there are no plans” for that, pointing to Bonnier operations already ongoing elsewhere in the English-speaking world. “We want to be in the top five of U.K. publishers, and we’re almost there,” he said. Last year, Bonnier Books enjoyed sales of $900m; it has 75 different publishing companies in 20 countries. Its U.K. headquarters is in Chichester, on England’s south coast.

Nigel Newton, Bloomsbury CEO, who hired Odedina shortly after Barry Cunningham (later to found Chicken House) departed, having first acquired Harry Potter and the Philosopher’s Stone, said: “Sarah has had a huge influence on our children’s publishing and on Bloomsbury as a whole in her 14 years at the company. She oversaw the publishing operation of each Harry Potter and brought her tremendous skill to the enormous worldwide publication of each of the seven novels.”

Emma Hopkin, who joined from Macmillan earlier this year as managing director of Bloomsbury Children's and Educational Publishing, added that she had “thoroughly enjoyed my time working closely with Sarah. She has been a generous and enthusiastic colleague; and she will be greatly missed by her authors, illustrators and colleagues alike. I have begun searching for a successor and will be working closely with Sarah and the children's team to ensure a smooth transfer.”

For her part, Odedina was quick to scotch any rumours that her departure owes anything to Hopkin’s arrival and a new reporting structure. “That’s one of the sadnesses--that I won’t be around to work further with Emma, with whom I’ve had a great time and for whom I have enormous respect. I feel I’ve learned a lot.” She pointed out that Hopkin’s role across the group’s children’s publishing was very much a managerial one and did not involve hands-on editorial. Yes, she acknowledged, she too will now be a managing director but she will remain fully engaged with editorial and will be working with authors, “the most magical” aspect of the publishing process.

Her brief now is to help find offices in central London, ideally around Soho, and to find a name for the fledgling company, which will begin publishing in late 2012 or early 2013. The projection is for between 30 and 50 titles a year and she intends to build a staff of 10-12, covering editorial, design, sales, marketing, publicity and e-books. She stressed that she has “too much respect” for Bloomsbury to poach any of the talented team with whom she has worked all these years. World rights acquisitions will be her goal but “not a deal-breaker,” she added, pointing out that she has long been known for publishing American authors and will continue to do so.

In a career trajectory not dissimilar to that of Kate Wilson, who headed up Macmillan and Scholastic before founding her own company, Nosy Crow, Odedina began her career in rights, working first at Penguin Books before moving to Orchard Books as rights director and moved to Bloomsbury in 1997.