Dormouse: "a very small squirrel"

Clearing out the family home, and there's a box of cigarette cards. One set is of "Britain's Endangered Wildlife", from sometime in the 1980s. It tells me that the Dormouse isn't a mouse: Dormouse Dormouse facts Rather than take all my facts from cigarette cards, I did check against the wonderful OneZoom.org tree of life explorer and it's true: Both rodents, but the dormouse is on the squirrels branch rather than the mouse-like rodents branch.