Hi I am looking for a story which I read many years ago about a boy called Tim who lived in the Victorian era at a school. It starts off with 'when the moon peers in through the window' and talks about a girl going to an older part of her school and seeing a boy in a red jersey who climes in and out of a box before vanishing by a cupboard. Two teachers go to investigate after schoo and find a diary in a hidden cupboard where they almost get trapped. The diary is written by the Victorian headmaster about Tim and how he froze to death.

If anyone knows this story and which ghost book it was in, can they tell me what it is please? Many thanks.