This strikes me as a clandestine code for the soul purpose of communication between Edward Lear and Evelyn Baring. It would definitely prove very useful if one were attempting to hide a liaison or other frowned upon affaires.

This is a possibility. Lear was gay. At this point it would be hard to say aye or nay. In light of Lear's limericks and other nonsense poems, it looks more than likely, to me, nonsensical in nature. Then again, homines loquaces are adept at finding meaning in the meaningless. Either way, it would require more research.