Not a Christmas episode, but a winter one: winter in various Old English sources and winter now. Happy New Year and thanks for listening!
Medieval Halloween: Signs in the Sky, Strange Children, etc
From William of Newburgh's 12th-century chronicle, The History of English Affairs, these stories aren't really about Halloween, but they do feel a little Halloween-ish. There's no Michael Myers, zombies, or vampires, but there are strange portents in the sky, toads locked in stone, faerie banquets, green children, and a good number of demons.