Access to books wasn't guaranteed to engravers in 19th century England, and piecework is how most engravers were paid. The Kell shop is credited with bringing more life to the game scenes, but other engravers were developing more life like renditions. Sumner, WW Greener, WC Scott and Kell produced work that buyers were willing to pay for and to add a distinction and value to there individual products. There was a definite change in the trade around the 1890's. Just my opinion.