<<I agree with Plazbot even if your Christmasses were subject to a draw if means someone was unlucky and perhaps someone was selfish in not giving up the odd one.>>
Just to let you know how it worked. Well before Christmas a list was drawn up showing the days over Christmas and New Year with columns appropriate to the number of staff required. We just popped our names in the columns showing when we would be happy to work - simple as that. I always opted to work Boxing Day and New Year if our watch was on and I always managed to get leave on Christmas Day. Nobody was inconvenienced in the slightest and everyone got what they wanted.
My wife never worked so she was always home when I was, which was magic and, God forbid, our sons never went to boarding school so we were a pretty happy family. I drove a Reliant Robin rather than a Porsche but that didn't worry me.