Douglas Harper's Etymology Dictionary
kit-cat
club founded by Whig politicians in London, 1703; so called from Christopher ("Kit") Catling, keeper of the tavern on Shire Lane, near Temple Bar, in which the club first met. Meaning "a size of portrait less than half length" (1754), supposedly is because the dining room in which portraits of club members hung was too low for half-length portraits.
Usage examples of "kit-cat".
The Kit-Cat Caravan began to mount up: and so the last they saw of the Clubb were scintillations of cut-crystal stirrup-cups and of the silver trays on which they were brought around, faint as gleaming of fish-scales on the black waters that lapped at Billingsgate Stairs.