We had one just the same around Xmas time! he just sat there staring at me and eventually took a slow run away up the hill and stopped to see if i was still chasing - which I was, swearing and making all sorts of threats. he had taken just one of our hens but had obviusly come back to select the next one..
they are getting much cheekier these days, I wonder if its more of the town foxes that have been shifted to the country sometimes.