Hay Festival 2013: 'Why have you killed off Mog?' Prince Philip asks author Judith Kerr Speaking at the Telegraph Hay Festival yesterday, Kerr joined Michael Morpurgo in reminiscing about the encounter. Referring to a reception some years ago, in which Kerr lined up to be greeted by the Duke, Morpurgo said: "The Duke of Edinburgh said to you, 'why did you kill off Mog?'" He added of his response: "I thought, this guy reads books!" The Duke of Edinburgh has eight grandchildren, including the Duke of Cambridge and Prince Harry. His eldest, Peter Philips, would have been seven when the first Mog book was published. He is not the only member of the Royal family to demonstrate an interest in children's books. Prince Charles published his own story 1980, entitled The Old Man of Lochnagar, while the Duchess of Cornwall is patron of several literacy charities and has previously spoken of her love for The Gruffalo. Morpurgo said of the final Mog book: "It deals with grief and how to deal with death, and gives young people a sense of what happens." The book, Goodbye Mog, was published in 2002 and was the last of Kerr's best-selling series about a pet cat. Judith Kerr reading at Hay Festival on Wednesday (Clara Molden) Her first, Mog the Forgetful Cat, was first released in 1970, with children enjoying another 16 picture books before the tabby finally died. The short tale, intended to teach children about losing a love one, begins: "Mog was tired. She was dead tired...Mog thought, "I want to sleep for ever." And so she did. But a little bit of her stayed awake to see what would happen next. The fictional pet, based on Kerr's own first cat, then helped a new kitten settle into her family home before being reassured her owners would "always remember" her. The book concludes: "'So I should hope," thinks Mog. And she flies up and up and up right into the sun. At the time of release, the book caused a sensation among fans of all ages, who mourned the loss of the much-loved character. Explaining her decision in 2002, Kerr said: "I'm coming up to 80 and you begin to think about those who are going to be left - the children, the grandchildren. I just wanted to say: Remember. Remember me. But do get on with your lives. Kerr, who is about to celebrate her 90th birthday, appeared at the Telegraph Hay Festival yesterday to speak about her new book, Creatures.