A classical dictionary of the vulgar tongue (1788) by Francis Grose (The Second Edition, Corrected and Enlarged, London) contains the following entry: "CHESHIRE CAT. He grins like a Cheshire cat; said of any one who shows his teeth and gums in laughing."
The phrase appears again in print in John Wolcot's pseudonymous Peter Pindar's Pair of Lyric Epistles (1792): "Lo, like a Cheshire cat our court will grin."
A possible origin of the phrase "Grinning like a Cheshire Cat" is one favoured by the people of Cheshire, which boasts numerous dairy farms; hence the cats grin because of the abundance of milk and cream.
Brewer's Dictionary of Phrase and Fable says grinning like a Cheshire cat is "an old simile, popularised by Lewis Carroll". According to Brewer's Dictionary, "The phrase has never been satisfactorily accounted for, but it has been said that cheese was formerly sold in Cheshire moulded like a cat that looked as though it was grinning". The cheese was cut from the tail end, so that the last part eaten was the head of the smiling cat.
There are many reports that Carroll found inspiration for the name and expression of the Cheshire Cat in the 16th century sandstone carving of a grinning cat, on the west face of St. Wilfrid's Church tower inGrappenhall, a village adjacent to his birthplace in Daresbury, Cheshire.
Lewis Carroll's father, Reverend Charles Dodgson, was Rector of Croft and Archdeacon of Richmond in North Yorkshire, England, from 1843 to 1868; Carroll lived here from 1843 to 1850. Historians believe Lewis Carroll's Cheshire Cat in the book Alice in Wonderland was inspired by a carving in Croft church.
In 1992, members of the Lewis Carroll Society attributed it to a gargoyle found on a pillar in St. Nicolas Church,Cranleigh, where Carroll used to travel frequently when he lived in Guildford (though this is doubtful as he moved to Guildford some three years after Alice's Adventures in Wonderland had been published) and a carving in a church in the village of Croft-on-Tees, in the north east of England, where his father had been rector.
"I said pig," replied Alice; "and I wish you wouldn't keep appearing and vanishing so suddenly: you make one quite giddy."
"All right," said the Cat; and this time it vanished quite slowly, beginning with the end of the tail, and ending with the grin, which remained some time after the rest of it had gone.
"Well! I've often seen a cat without a grin," thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life."
We do know that Lewis Carroll (The Reverend Charles Lutwidge Dodgson) didn't coin the phrase himself, as there are citations of it that pre-date his stories. John Wolcot, the poet and satirist, who wrote under the pseudonym of Peter Pindar, included it in his Works, published variously between 1770 and 1819 - "Lo! like a Cheshire cat our court will grin".
William Makepeace Thackeray also used the description well before Dodgson, inThe Newcomes; memoirs of a most respectable family, 1854–55:
Mr. Newcome says to Mr. Pendennis in his droll, humorous way, "That woman grins like a Cheshire cat."
There's no convincing explanation of why Cheshire cats were imagined to grin. It seems likely that no one really believed that they actually did. We can take the next line in Thackeray's piece - "Who was the naturalist who first discovered that peculiarity of the cats in Cheshire?", to be sarcastic.
The numerous folk-etymology derivations that explain how Lewis Carroll came up with the idea have to be spurious, as we know he didn't. Alice's Adventures in Wonderland has a long troupe of fantastical animals. It's very likely that Dodgson had heard of Cheshire cats being said to grin and adapted the idea into his story.