Temperatures fell to -13.0°C overnight at Shawbury (fig 1). Not a real surprise, because it’s a well-known fact that Shawbury plus a clear night and light winds, plus a snow cover equals a very low temperature. It still holds the record for being the coldest place in England, when almost 36 years ago now, the temperature fell to -25.2°C on the 13th of December 1981, when there was a similar depth of snow on the ground. As far as I can see this table of top ten coldest places in the UK from the Met Office blog is still correct (fig 2).
Having said all that last night was not a perfect radiation night at Shawbury as you can see from the observations (fig 3).
The wind never really dropped out, although this didn’t prevent them going into fog at 23 UTC, when the temperature suddenly dropped from -3.0°C to -9.2°C. Fog or freezing fog, as it may well have been, will slow or even halt the fall in temperature depending on its thickness, and if these observations are correct the minimum may have occurred around 05 UTC, because the next hour it rapidly warmed from -12.4°C to -6.9°C, before falling again (fig 3).
Looking back almost 36 years, here’s the 00 UTC chart for the 13th of December 1981 (fig 4). As you can see the minimum at Shawbury that night probably occurred close to midnight. It’s interesting to speculate that if the ridge of high pressure had just hung on for another 6 hours instead of collapsing like it did, the minimum temperature at dawn may have matched the -27.2°C extreme minima recorded in Scotland.