Not all heroes wear capes, but some wear socks when wading out into brackish water. Uncle Russ saw something struggling and didn't hesitate to go get it. American viewers were waiting for the alligator to emerge, but this is Britain, where canals are not necessarily deadly.
See the rescue in a TikTok video.
Notice the desperate fox turning toward the man as he approached. Russ emerged from the water with a fox kit that had apparently fallen in the water, who knows from which side or how far away. The couple took the kit to a wildlife rescue center, where it was put on antibiotics and was expected to be released eventually. We hear that Uncle Russ was bitten during the ride and had to check his tetanus shot record. British canals may be gator-free, but they aren't clean.
As an aside, when people call this a fox cub or puppy, and you correct them by telling them it's a kit, the response will always be "It looks fully assembled to me." -via reddit