I have a few good coats - an older Barbour wax, 2 long wool coats, a thin Barbour rain mac and a small puffer.
Surprised recently by something I discovered when out in the damp, biting cold of the north UK.
I wore a merino base layer under a donegal wool jumper with thick trousers and warm accessories and felt warmer than when wearing any of my coats!
Couldn't get my head around this as I have always loved coats, the bigger the better, and they can cover a multitude of sins, lol. But I can't lie, the decent combination of wool layers did make a terrific difference, and without the bulk (my woolies are not terribly chunky, just very good knits).
It left me slightly confused and disinclined to buy anymore expensive padded winter coats, maybe just something for the rain.