A half-century ago, Russell Hoban introduced a decidedly not sleepy young badger in Bedtime for Frances, which featured illustrations by Garth Williams. Picture book readers and their parents took an immediate shine to this feisty character, who went on to star in five subsequent stories. To celebrate Frances’s 50 years in print, HarperCollins this week is issuing Frances 50th Anniversary Collection, a boxed set of paperback I Can Read! editions of Bread and Jam for Frances, Best Friends for Frances, and A Bargain for Frances. Speaking by phone from his home in London, where he has lived for four decades, Hoban revealed how Frances came to be, and reflected on the success of the books in the series, which have sold more than four million copies for HarperCollins.

“I arrived at Frances by way of earth-moving equipment,” Hoban recalled with a chuckle. “At the time, I was a freelance illustrator and in my spare time I used to travel around Connecticut looking at bulldozers, power shovels, and other equipment. I considered them very beautiful.” That fascination led to his first book with Ursula Nordstrom at Harper, What Is It and What Does It Do?, which focused on these machines.

“Since I was then a published author, I decided I should do another book and I cast about for ideas,” Hoban explained. He found inspiration in his back yard. “Our next-door neighbors had a daughter who always found ways of stalling at bedtime,” he said. “Though I didn’t use any of her specific stalls in the book, this little girl was the reason that Bedtime for Frances came about.”

The author credits Williams for giving the reluctant sleeper her badger identity. “He had drawn all kinds of cuddly looking animals, and for a change decided to draw badgers in this book,” he commented. And that continued.” Asked about the repetition of the letter “B” at the start of each subsequent book title, all of which are illustrated by Hoban’s late first wife, Lillian Hoban, the author replied, “Well, I’m superstitious, and since Bedtime was well received, I thought I’d begin the next one, A Baby Sister for Frances, with a ‘B,’ and so on down the line.”

Discussing the success of his Frances stories, Hoban mentioned the songs that the title character frequently makes up and sings: “Bedtime for Frances has no songs in it, but starting with the second book, they all have little songs in which Frances expresses her feelings about the current situation. Those songs account for a great deal of the books’ popularity.”

He also pointed to the appeal of Frances’s close-knit family. “The feeling that runs through all these books that problems can be resolved through that kind of loving attention is important,” he noted. “I think that is a reason that these books have received widespread approval from both readers and professionals.”

Tamar Mays, senior editor of HarperCollins Children’s book and editor of the anniversary collection, also emphasized the reassuring nature of the badger’s supportive family. “Like any child, Frances pushes boundaries and can be very stubborn,” she observed. “But her mother and father are so lovingly drawn and always have the perfect response. The books impart a wonderful sense of their loving kindness.”

And inarguably there is the intrinsic appeal of Frances herself. “She is such a strong individual,” the editor said. “She’s opinionated, she’s imaginative, and there is absolutely nothing predictable about her. The combination of this unique character and Russell Hoban’s treatment of universal childhood moments have helped these books to endure.”

Though A Bargain for Frances was originally published in the I Can Read! format, all the other Frances books came out first as picture books, and those editions remain in print and “are still very popular,” Mays reported. In 2008 and 2009 HarperCollins published (respectively) Bread and Jam for Frances and Best Friends for Francis in the I Can Read! format, editions Mays called “gentle abridgements that Russell did with the help of his daughter, Phoebe. The strong sales of A Bargain for Frances made us realize that there is also an interest in these stories in this format.” An I Can Read! edition of A Baby Sister for Frances is due in fall 2011 and of A Birthday for Frances in fall 2012.

Hoban, who has in recent years been writing novels for adults rather than picture books, said he finds it gratifying to see Frances reach the 50-year mark. “The Frances books are the most popular of all my writing efforts. They outsell my novels and everything else,” he remarked.

Might the author return to children’s books? “Well, as it happens I am working on a new children’s book, with Quentin Blake,” he answers. “It hasn’t got to the publication stage yet. I’ve only just sent Quentin the first draft to ask if he wanted me to make any changes.” But Hoban remains mum on the book’s subject. “I can’t say,” he explains. “You see, I’m superstitious.”

Frances 50th Anniversary Collection by Russell Hoban, illus. by Lillian Hoban. HarperCollins, $11.99 paper Sept. ISBN 978-0-06-186398-1