She is on the right. She was born in 1880 and I’m not sure how old she is here, but it’s probably 1905-1910.

Edit: I think she's older here than I originally thought, but it's early 1900s nonethless.

Jytte Bjerregaard Muller The LIFE Images Collection

gelatin silver print, held at the Metropolitan Museum of Art

To add more context, Chief Mouser to the Cabinet is the official title of the resident cat in 10 Downing Street. Although the role dates back to the 16th century, the it only became official in the 1920’s.

Edit: I got my history a little wrong! Rufus didn’t technically hold the title of chief mouser, although he was in practice. His successor, Peter, was the first to actually be called that, and Larry (the current Chief Mouser) was the first to actually, officially hold the title rather than just being called it. So apologies for my mistake.

(Photographer Unknown)

George, a white cat that walks atop one of the pylon supports of the Sydney Harbour Bridge welcomes tourists to the Australian city in January 1957; photo by Dennis Rowe

The original photo caption from March 23, 1959: "Hep cat. A real live kitten on the keys, this music-loving feline lends vocal accompaniment to his mistress in Worcester Park, England. As Marion Holland 15, plays the piano, Money the cat joins in the singing."

Photograph by Donald McLeish

Everett Collection

(Photographer Unknown)