I followed the production of the most recent (2005) "The Lion, the Witch and the Wardrobe." While "Father Christmas," only has a brief appearance in the story, it's a pivotal one as he provides the Pevensy children with their armor and weapons to fight and ultimately defeat the white witch.
In developing, casting and costuming the character, the production team shied away from the "jolly old elf" meme and sought something more along the lines of a returning, old warrior. I think they pretty much hit the mark...