I saw this explanation on a tv program so thought I would crash your hopes as it did mine. LOL
Basically Christmas used to fall into what we know as January, for some reason 10days was knocked off our calendar. It is more likely to snow in January than December. SO when we knocked 10days off our Calender making Christmas fall in January, this reduced the chances of snow.
Another reason is we have 3 weather fronts hitting Britain. For snow we need the same temp in the sky as on the ground for it to snow...
With 3 fronts hitting us and the climate change, those days of xmas snow looks to be a thing of the past... except for up North where they have the highest likelyhood.
East Britain are 8-10% to have snow this christmas, with the highest being North with 14%. Still not great however for bookies to pay out, all we need is for it to snow between 12.00 christmas eve to 12.00 Christmas evening and it must land on the designated areas.
Oh well hope I didnt bore you too much! lol
Oh well.. Lapland for me next yr to see now!