The Happy Nappy is one of Perfect Peter's favourite books.
In "Horrid Henry Reads a Book", one of Peter's book reports Henry copies is on The Happy Nappy, and, to achieve the target of twenty-seven, he makes up a Happy Nappy book series where he travels the world. The Happy Nappy series Henry makes up wins him the book competition where he and Moody Margaret get to work in the School Library for a week.