When I first decided to write a book with 300 children, I imagined it would turn out a bit like one of my Smelly Troll books, but perhaps with a different kind of monster. Reflecting on the book, it's not like anything I'd have dared write myself.

The book starts off with Simon, a sickly ten-year-old boy, taking a long walk to a city to buy some medicine for his grandpa. Meanwhile a tig (type of good monster) is beaten almost to a pulp by a bully. After heroically scooping the tig off the grou...