The film follows the writer's time in the army during the First World War, before exploring how his love for his young son Christopher Robin (played by Will Tilston) inspired the children's books that made him a household name.

At one point in the trailer, the young boy spots Milne's first sketches of his teddy bear – which was the basis for Winnie the Pooh. "Are you writing a book?" he asks, "I thought we were just having fun."

"We're writing a book and we're having fun," his father replies.