Gavin, academic or not, Braemar holds the record.
And I would suggest the end of December 1995 delivered a considerably
colder 48 hour period than the one you have quoted as being the coldest in
Britain since 1740. Albeit academically/merely in Scotland.
Temperatures at this site remained below -10ºC for 72 hours on that
occasion. And I'm sure this was exceeded at other locations - albeit in the
academic part of the country.
:-)
Alex.

;-) ... we love you in Scotland, really, Alex! I think Gavin was trying to
say it would be cold in the Highlands compared to the balmy S.E. (or was
that barmy). Like Iceland can probably beat Braemar's minimum.
Gavin - I have a feeling it was Benson, Oxfordshire, or nearby, that was the
coldest that spell and holds the England min record. Not exactly The Home
Counties but a notoriously cold region for night mins.

Dave, jealous of the Motherwell snow.