The cover designs of many of Goodall’s card-game rule-booklets are often extremely complex, and it would have been quite straightforward for an artist to place his (or her, but I don’t know of any female artists employed by Goodall) initials or monogram into the design, in such a way that there would be little possibility that it would be noticed.
The “L” (for John Leighton’s surname) near the bottom front (at the center) of many early printings of The Royal Game of Bezique is quite obvious. The front cover of The Game of Check, as pictured on page 34 of Mike Goodall’s book on the Goodalls, shows the same “L” — understandable, because the booklets had basically the same cover designs. Mike says that John Leighton (Luke Limner) designed the Bezique and Check covers, and that “from about 1873 until the 1880’s the covers were designed by William Taunton [. . .].”
Recently I posted some information on Foster’s Pocket Guide to Modern Whist. In looking at an “enlarged” scan of the back cover I noticed what seemed to me to be an anomaly.
The design components within the top three (sideways) hearts in this cropped version look pretty similar to those of the bottom three. But the components in the center (fourth one down) look quite different. It looks like it could be . . . a monogram!
Of course, no two are exactly alike, but that center one is very different from all of the others.
If it is a monogram, it may not be oriented properly in the above portrayal!