Actually it's an odd one, because days falling are (in most places) higher than days with snow cover. After 23 Christmas's in Yorkshire I think it's 7 with snow on the ground (probably 8), but from memory the majority of those no snow fell on the day.
And Graham, you can add 1962 to snow falling and a near miss early 80's, 82/83 on the 27th I think? The snow of 1978 was too near the New Year to be included.