Teacher1 gives you a metoffice link website.
It didn't work for me as the page just went blank,with just
a small box in the top left of the page.
So I wouldn't bother if I were you.
Though I did get an answer from a previous person named roslyn25254,and said:-
1970 - 1976 - 1996 - 1999.
Actually had snow falling in 1981.So,it was white though the snow was from previous days' falls.I would count this as well myself.