- You may be looking for the journal of "John Smith".
A Journal of Impossible Things was a book by Verity Newman. It recounted the experiences that her great-grandmother, Joan Redfern had with John Smith in 1913, who Newman described as "a visitor from another world". It was based on Redfern's diary, which Newman had discovered in her loft.
During the launch of the book, Newman had a book signing at a bookstore. The Tenth Doctor, nearing the end of his life, got his copy of the book signed. The two shared a poignant moment in which he was curious whether her great-grandmother's life had turned out well, and she wondered whether he was happy. (TV: The End of Time)