AFTER FIVE YEARS as one of the world's most successful children's authors, Julia Donaldson has released a book of tunes, The Gruffalo Song and Other Songs. It would be easy to dismiss the songbook as a cynical expansion of the Gruffalo brand or as the folly of a million-selling author with singer-songwriter fantasies. But in Donaldson's case, the music came first. Her previous career as a songwriter and performer led her to books - and introduced her to Malcolm, her husband of 31 years. The Donaldsons became romantically involved when the two - then Bristol University students - busked together in Paris. 'That performing led to the songwriting,' Donaldson, 51, says at a boutique hotel in London's Shepherd's Bush. 'Then I started to write songs for events. We'd be asked to perform at a dentists' dinner and I would write a funny song about teeth. We got booked to sing at the Covent Garden Hat Festival, so I wrote a song about hats.' When one of her songs, A Squash and a Squeeze, was made into a book, Donaldson reluctantly put down the guitar she says she plays 'very badly'. 'I really just got the bug for books after that,' she says. 'Now, it's all come full circle. Songwriting led to the book writing and now I've written more songs to go with the book. Malcolm and I often do performances, so it means I'm not just sitting at home chewing my pen. I'm more often on the road.' Glasgow-based Donaldson and illustrator Axel Scheffler have published more than 30 children's books in 12 years, many of which won awards and created their own following. The Giants and the Joneses, which retells Jack and the Beanstalk from the giant's perspective, is expected to become a Warner Bros film. But Donaldson is best known for The Gruffalo. The tale of a sassy mouse staving off forest predators by boasting of an imaginary monster pal, the Gruffalo, has sold more than a million copies since its release in 1999. Awarded numerous prizes, translated into 26 languages and performed on Broadway, the book remains in many best-seller lists. Its sequel, The Gruffalo's Child, released in September, looks set for the same success. Donaldson and Scheffler are credited with swinging children's books away from realistic stories and back to more colourful and fantastic themes. 'The Gruffalo's got a strong story line,' she says. 'I think it came out at a time when there weren't that many picture books with strong stories - a proper story. There were more picture books about, 'So and so is very shy. Try smiling, said granny. But that didn't work. Try something else, said mummy. But that didn't work.' They were almost psychological. At the end, they discover, 'If you smile, people will smile.' There were a lot of soppy ones out there and now there are more proper stories around. 'I don't really think about the message when I'm writing - more about the story line. But if the story is strong then it's likely to be deep, as well. It doesn't work to take the message as one's starting point. It can end up heavy-handed and didactic. 'My children loved picture books when they were little. I got ideas about what they liked. I don't consciously think it's got to work. Some people might write a rambling story and think this is a picture book, but I know it isn't. That's probably because of my schooling at the bedside. 'Each of my boys has inspired at least one book. My oldest, Hamish, as a child had an imaginary friend whom he saw in the mirror. This inspired Princess Mirror-Belle, about a girl whose reflection steps out of the mirror and claims to be a princess. My middle son, Alastair, was an avid collector of anything and everything, and this inspired The Giants and the Joneses, about a girl giant who collects three human beings and then loses interest in them. My youngest, Jerry, is addicted to breakfast cereal, which led me to write Brick-a-Breck, about a boy who designs his own cereal. 'I loved reading to my own children. It was lovely to share books with them at the end of the day and to have all those characters to refer to in our conversations. It gave me a love of story and language.'