These stories are designed to be read at bedtime: to be read to younger children and for older children to read to their parents. Some of the sentences are longer and will require practice and there are some longer words for older kids to add to their vocabulary.

There is also some detective work for kids to do: the illustrations contain hints about what is to come, there are maps to trace routes on, and characters to keep track of in the handy cast of characters in each book.

Parents may also find themselves intrigued: much of the action takes place in Big Hat which is rather like New York City but not quite. Many of the locales mirror locations in the city that families often visit. The story mixes my own British and American roots for inspiration and in terms of technology Big Hat turns out to be a century or so ahead of our own. So everything is familiar but not quite as it first seems.

The character of Zachary is based on my son Zander who was tragically killed in a bicycle accident in September 2008. He & I used to joke about Mildred & Stella and the pig and the parrot when we played cards and board games and those characters provided the kernel for the stories to come. The names of the stations on the Big Hat subway map are all Zander's. These are the kind of stories he would have liked - where the ghosts are afraid of the children, where you have to think about problems like a detective, and where children can get together with grown-ups and save the day. If your child likes Tintin or Paddington Bear or Moonmintroll they should be at home with the Zachary Stories.