It would probably be quicker to list Christmas number 1s which WERE about Xmas
http://en.wikipedia.org/wiki/List_of...as_number_ones
So we're looking at:
2004 (Do they know it's Christmas?)
1990 (Saviour's Day)
1989 (Do they know it's Christmas?)
1988 (Mistletoe and Wine)
1985 (Merry Christmas Everyone)
1984 (Do they know it's Christmas?)
1978 (Mary's Boy Child)
1976 (When a Child is Born - a song I incidentally despise)
1974 (Lonely this Christmas)
1973 (Merry Christmas Everybody)
1957 (Mary's Boy Child)
1955 (Christmas Alphabet)
And that seems to be every Xmas number one from 1952 onwards which is actually about Christmas, which makes 40 Xmas number ones which aren't about Christmas.
And that's before we get onto the rest of the chart.