Not sure when this episode aired since I was behind on my viewing (and unfortunately didn't get the VCR set for the days I was at the festival ... that chess scene mentioned elsewhere with Professor Stokes and Julia sounds really good -- I don't remember it from the previous viewing but I must have it on tape from then.)
Anyway, in Episode #546, Nicholas removes Angelique's powers, telling her "You are no longer a member of our coven," and saying that she is now only a woman "born in Martinique in 1774." I didn't remember this from my previous viewing, but it is crucial biographical information about Angelique. She was 21 in 1795.
I love these tidbits, but it just isn't reconcilable with what we learn in 1840, i.e. that Angelique was formerly Miranda du Val, who lived in 1692 (I think it was). The sequence also makes clear that she did not die and was not later reincarnated as Angelique on Martinique!