I was going to suggest fleece-lined leggings, too. I have a pair and they are lovely and warm.
Some places may also sell fleece-lined jeans (denims), although I am not sure what's available in your area.
To think that London, or anywhere else for that matter, does not belong to any one demographic
A Good Year Film4 6.40 tonight
Recommendations please, for a stopover on the way to Loch Tay