Oh, and Charles had a sister Mary Charlotte Dodgson. (With 11 kids in the family I guess they had a shortage of names.)
Please don't take this as criticism, but I would think the surname Dodgson would be familiar to Holmes, even if Charles Dodson wrote under another name and the family didn't live in London. Dodgson's book The Game of Logic was published in 1886, and would have interested Holmes even if his other publications did not.