There was a large temperature fall and veer of wind on the cold front associated with storm Christoph on Wednesday evening. I analysed the 18 UTC chart and have included it to give you a better idea of the airmass change just ahead and to the rear of it. I’ve not look at all stations but typically there was a fall in temperature of up to 5°C in an hour at most sites but as much as 7.5°C or maybe more at others. At Coleshill there was an hourly fall of 7.5°C (8.4°C to 0.9°C) between 22 and 23 UTC that evening and the heavy rain turned to rain and snow for a time. There may be higher instances than that, but I would need to write some extra code to test all the possibilities to find them.
Here is a selection of thermographs from stations across England that evening.