I actually can't remember which came first - did I read the book then see the TV series or vice versa? It doesn't matter in this case, because - very rarely - the TV series was as good as the book.
Minty goes to spend some time with a relative while her mother is in the hospital. She becomes fascinated with a nearby large country house and its gardens (and the ghosts that live in it).
One of my favourite books growing up, Moondial has a likeable and believable main character and the writing is superlative - interesting and great for children, without being patronising. Thoroughly recommended.