You can now read Ian Malcolm’s 1908 overview of Lear’s career (mostly from the point of view of the Baring family) in the Nonsense section of the site bookshelf:
Ian Malcolm, “Edward Lear.” The Cornhill Magazine, vol. 24, January 1908, pp. 25-36, as reprinted in The Living Age, vol. 256, no. 3319, 15 February 1908, pp. 467-75.
I have also added, in the Comics section, a long article on Ally Sloper:
Elizabeth Robins Pennell. “The Modern Comic Newspaper. The Evolution of a Popular Type.” The Contemporary Review, vol. 50, October 1886, pp. 509-23.