"Much play has been made of one incident where someone left the door of their house open and a fox apparently went inside, climbed the stairs and savaged their young children."

What did the medical examiner have to say? This sounds like rats, not a fox. (If it ever happened.)

I read an article in the Smithsonian magazine once (or maybe it was Natural History magazine) where a man observed foxes in the wild for a long time. Much of their diet consisted of earthworms.