My usual source clearly does not have correct data for min temps, since there were several lower temps than those they shown bu the MetO even at 09z this morning (Tulloch, for example)

Mike Chalton, who runs the MetO station at Saughall, told me himself that he recorded -7.8c overnight and for the moment I consider this to be correct, so it should be deemed lowest temp unless/until more data received

Nationwide extremes for 23-11-2007

COLDEST

Weather station	Altitude	Overnight Temperature
Drumalbin	245 metres	-3.1°C
Shap	255 metres	-2.3°C
Prestwick	27 metres	-2.2°C
Tulloch Bridge	236 metres	-2.2°C
Warcop	227 metres	-2.2°C
Glasgow/Bishopton	59 metres	-1.8°C
Machrihanish	10 metres	-1.8°C
Eskdalemuir	242 metres	-1.4°C
Keswick	81 metres	-1.4°C
Loch Glascarnoch	264 metres	-1.1°C

Saughall's graphical hourly observations from the Meto show a sharp drop from -3C @ 06z to -7C @ 08z, possible I suppose.

Mike is away tomorrow but I'll ask him about it next week :)  

Don't think there much doubt about c -5c