Children's books podcast: Eoin Colfer and Oliver Jeffers on their picture book, Imaginary Fred

Eoin Colfer, author of the bestselling Artemis Fowl novels, and award-winning picture book creator Oliver Jeffers have paired up to create a book about imaginary friends, Imaginary Fred. Find out how they met by chance, collaborated across continents by skype, and, of course, whether they have their own imaginary friends Buy Imaginary Fred at the Guardian bookshop