Thinking of those beautiful muslin (sp?) dresses we see in Austen adaptations, how did anyone stay warm during a British winter? Long woollen underwear?
On the one hand, satirists of the time liked to depict women in thin, clinging muslin gowns all year round, accessorized with only a shawl or spencer (a short jacket), allegedly showing a true practice. According to these men, women did not make any alteration in their dress to accommodate the weather, and as a result they were extremely susceptible to fevers and colds, and often died.
On the other, fashion magazines show much more sensible behavior. In La Belle Assemblée, for instance, the fashions for February given in the 1812 January issue include a "winter walking dress" consisting of a cambric gown (cambric being somewhat heavier than muslin, though still just a cotton) and a pelisse - a long, high-waisted coat - made of red Merino wool lined with yellow silk and trimmed with fur, as well as a cashmere shawl and a Merino hat or bonnet; the related "notes on dress" section mentions a number of other warm hats, as well as leather boots lined with fur. The fashions for March given in the February issue include promenade dress of a purple velvet pelisse and a silk "Minerva bonnet", a fairly close-fitting style, although in general the text on the fashions of the month focused on how increasingly warm the weather was.
In addition to being made of warm fabrics, pelisses and spencers could also be "wadded", or padded with a layer of wool batting, which might or might not be quilted into a heavier textile. There was also a hooded coat fully lined with fur called a "witzchoura", fashionably brought out for the worst of the winter, although it seems to have been a high-prestige garment rather than something commonly worn to block out the cold. Winter bonnets and hats tended to be covered with silk (an insulator) or wool, and to have no brim or very short brims, so as not to catch the wind.
Long underwear as we know it today is a Victorian invention, but women could wear shifts and petticoats made of warm wool flannel. Drawers were only just beginning to be worn, but they could also have been flannel if necessary. And stockings, of course, would be made of thickly-knitted wool.