I think I've mentioned this before, but "The Dance of the Gull-Catchers" is printed at the back of my copy of From Hell, and it's Moore writing a comic about the history of Ripperology and his own process of research. Not helpful re: this specific question, probably, but well worth reading in its own right, if you haven't already. ("You" being both michaeldthomas, who probably has, and truepenny, who may or may not have.)