] Does anyone know what ‘Napoleon blankets’ are? Was this the hysteria-driven Regency equivalent of plastic sheeting and duct tape?

I just googled too, and I kept coming up with references to the use of blankets as makeshift tents, first by the French and later by the English troops, during the Napoleonic wars. I'll put a link to the most useful article, below - but the short version is that (following a French idea) the British troops were issued with blankets already rigged up for use as tents, should the need arise.

(According to one sight, in France these blanket-tents were carried rolled up on the back, and French bakers were asked to produce a loaf of bread which would fit into the hole in the centre of the rolled-up blanket - hence the baguette was born. Who knew?)

Anyway, I can imagine that young English girls might have felt it would be useful to sleep with makeshift tents under their pillows, in case they needed to make a run for it.