Responses
he thought he knew her because her facial features are similar to those of one of his female companions (I believe it was Louisa?) whom he promised to meet. They were also in the dark so he most likely wasn't able to see her clearly from behind.
So the duke doesn't know she is a woman? I could'vesworn he does by the first 15 chapters or so but then when we first got an insight of his inner thoughts when she was eating the sandwich, I thought maybe he didn't know and now after the incident in the cabin when he said "it's a shame" insinuating that "it's a shame she is a man" then now I'm sure he doesn't know.
I wonder if she saved him in the past or something? Because the first time they met, he seemed sure that he knew her