cheshire cat, you old

   No-one has satisfactorily explained why Cheshire cats are supposed to grin. The saying ‘to grin like a Cheshire cat’ already existed when Lewis Carroll had his heroine, in Alice in Wonderland, ask the Duchess why her cat was grinning, only to be told: ‘It’s a Cheshire cat, and that’s why.’ In vocative terms, to call someone ‘an old Cheshire cat’ is clearly not the same as calling that person an ‘old cat’.

   Thus Clive Newcome. in Thackeray’s The Newcomes, says to his aunt’s servant, Hannah: ‘What are you grinning at, you old Cheshire cat?’ A moment later he also calls her ‘you old goose’, but we are told that ‘by these playful names [Clive] had been wont to designate Hannah these twenty years past’.