] I don't think so, Linden. As far as I know, they didn't wear anything under their shirts, knitted or otherwise.

The shirt was pretty much an item of underwear (no gentlemen would appear in shirt only, without waistcoat, before any women other than close relatives, or women nursing him when he's ill) -- and on all occasions except the most informal, a man would already be wearing three layers over his torso (shirt, waistcoat, and tailcoat), so there was no reason to wear anything under the shirt...