Turning Dragonese

This autumn, meanwhile, publisher Hodder Children's Books will launch a national Dragonese day (the language spoken by dragons) to mark publication of the ninth book in the series, How to Steal a Dragon's Sword.

The star of the series, a young Viking warrior called Hiccup Horrendous Haddock the Third, has come far since he first appeared as the protagonist in Hiccup: The Viking Who Was Seasick in 2000.

How to Train Your Dragon (2003)—a cross between Wimpy Kid and Charlie Bone—was Cowell's first foray into fiction. She says: "I was a picture-book writer but I liked the character Hiccup and the relationship between him and his father. Hiccup's world is based on a place I used to visit as a child, a tiny Scottish island off the west coast, although I'm not divulging which island it is; even the locals don't know it's the basis for this series." Cressida told a captivated audience at Bath Festival for Children's Literature more about the island that inpsired her stories.

Viking kink

"The island is linked with the Vikings. There's an old fortress that was probably built by the Vikings and you can also feel their influence in the Clan stories. My dad used to tell us local stories, including one about a dragon in a cave, and I used to imagine that there were dragons living in the caves. I started to think, if it was like this, a time when there were dragons and humans living together, what would their relationship be like? That was the start of How to Train Your Dragon.

"I guess that the books are about growing up. I establish that right from the beginning, as Hiccup is telling his story as a grown man looking back on his childhood, so you get that bittersweet sense of the story being told from the perspective of a boy growing up and moving into a new world, but also of the old man who sees himself growing up and leaving something behind.

"How to Steal a Dragon's Sword is a little bit different from the earlier books, but it's the penultimate one and the story is epic as well as being funny. Hiccup has made a journey, and in this book the story had to go to a more serious place, otherwise it wouldn't feel like he'd progressed.

"We discover that Hiccup has picked up a variety of objects ­during his earlier adventures, like an old shield and sword, which come to have real significance in this story; Hiccup has been doing a quest without realising it. He's a hero and has been developing all the attributes of one as he went through each of his earlier ­adventures.

"Hiccup is growing up and the world he is living in is trying to grow up as well, and I wanted there to be a big moment in this story when we see this happening. I didn't feel the books could take a Stoick death [Stoick is Hiccup's father], because the stories are too humorous and you'd feel cheated as a child, but there has to be a moment where Hiccup has to grow up. This is portrayed through a sword fight he has with his father; I engineer a point where Hiccup can become the king and Stoick remains the chieftain."

Bittersweet moment

"How to Steal a Dragon's Sword is the penultimate book in the series—unless I find I can't write the last story in one book. The books are very personal to me and it's bittersweet to see them coming to an end because I love writing them, but the story needs to come to some sort of completion.

 "I may also look at writing about this world in another way; it would be great to write about some of the other characters in more detail, like Camakazi, so if people want it, there's a way back into this world.

"I absolutely loved the film How to Train Your Dragon. It was an extremely positive experience. I went into the film partly with a spirit of adventure, wondering what was going to happen. But I also felt that they got the books and wanted to do something funny and epic and moving at the same time.

"I don't compare the film to the books because it's in a completely different medium and because the story is so obviously different. There are also things they do in the film that you can't do in a book – like showing what it's like to fly on the back of a dragon.

"Dreamworks really bonded with the world. It took seven years and 400 people to make How to Train Your Dragon, which is unbelievable dedication. It's unusual to have the same team of people who were there seven years ago signing up to make the second film, which will come out in 2014."

How to Steal a Dragon's Sword is out now, published by Hodder Children's.