2010. Always 2010. 15cm of snow on the ground, the Severn frozen, went into work at 7.30 and the car read -12C right in the middle of town. Continuous snow cover from the 17th to 28th.
2004 second, although the snow didnt arrive till the evening it was nice to see it fall and settle on the day. Only lasted 2 days though, the rest of the winter was mild and grim.
1995 had a week of frost from the 24th but no snow, that had gone on the 23rd and came back on the 30th. If it hadnt been for that horrid mild day melting the snow on the 23rd it would have rivalled 2010.
1992 I remember being very frosty with freezing fog and rime, a rare event that winter which was nearly devoid of cold and snow.
2006- a horrid December but the 25th was frosty.
Worst would be either 2002 or 2011, both ridiculously mild and very dull.