Mystery Author, I applaud you like mad! This pushes so many of my enthusiasm trigger buttons! I love historical fic, with plausible explorations of characters in their era, and if the fic is then about a historian and includes an intelligent exploration of what history means to him, well, my day is made! Your Binns is a triumph; his voice is perfect, and the life you give him a perfect fit for the ghost-y canon personality. Also, his approach to history fits not just his personality but also his era. Awesome. Walburga is fantastic, too, with her world-view and the constraints of her class.
I am a Historian. Or, at least, I try to be. Sometimes I think I might just be an enthusiast. I'm with Cuthbert.