“The Cat in the Dairy-House Window” is not, as far as I am aware, an actual coat of arms representing any family or region. Instead, it is part of a very, very old satirical anecdote, though what it is satirizing depends on the teller. Sir John Ferne’s The Blazon of Gentrie, published in 1586, is the earliest written instance of this tale which I can find.
The text is written as a conversation among several travelers of different social classes, which centers on the values of the nobility and the technical points of heraldry. The herald (and Ferne’s authorial stand-in) Paradius, asks the knight, Torquatus, to blazon the coat shown above. Torquatus gives the following blazon: “Sable, a Musion passant guardant Or oppressed with a fret gules of eight parts, nails argent.” (188) The farmer, Collumell, surprised that “Arms should not have been of such trifling things,” breaks in to offer his own blazon: “the Cat in the milk house window.” Paradius takes the opportunity to mock Torquatus by telling him that he and Collumell are equally correct, since Torquatus had confused a lattice for a fret. However, Paradius goes on to mock Collumell’s understanding of the arms as undignified, attributing them to a vassal of King Childebert of France who captured King Gundemarus of Burgundy in battle. (The cat was the symbol of Burgundy).
However, in subsequent tellings, the tale seems to have evolved into a parody of the elevated language of blazon. In Quentin Durwald (1830), Sir Walter Scott sarcastically attributes Paradius’ account to the Burgundian herald Toison d’Or, who is “too learned to be intelligible.” (ch. 33) In this version, the jester’s blazon of “the cat looking out at the dairy window” is received as a good joke, and the pompous herald ends up being chased by the royal hounds. This revised version is much more popular than the original; Fox-Davies quotes Scott’s account in A Complete Guide to Heraldry in 1909, and John Vinycomb’s Fictious and Symbolic Creatures in Art, published the same year, refers to Scott’s interpretation as well. (258; “The Heraldic Muison”)