Foxes run wild in London much like squirrels do in New York City. They've been beloved (and also despised / hunted) throughout English history. It looks to me like this one is pouncing on prey. Or playing?
MATERIALS: sterling silver, 10k gold, rose cut diamonds, rubies, new 14k gold chain
AGE: c. 1880
CONDITION: Very good - likely converted from a stickpin into a pendant
SIZE: 5/8" length including the bale, 5/8" width, 18" chain