Now THAT"S detective work ;-)

{As to the windows.. you are right about the laws, but I have a feeling that these windows have been replaced several times since 1780}

Yes, of course. I would agree with that, just like the fan light could have been added later.

{Do you happen to know the date the photo of the inside was taken, Patricia? }

No, sorry. I tried to find a date from the acknowledgements but nothing there either. I have it in Nigel Nicholson's The World of Jane Austen, which was first published in 1991. He states that it is early Georgian (which is considered to be in the 1714-1765 range in my Elements of Style Interior & Exterior book) and another source stated the same but I'll have to think where I found the other one. Perhaps there was more information there.