I have asked in the What We're Reading forum but I'm posting here for traffic
I'm trying to remember this book
The protagonist is a female artist in the 17th/18th century. (I think the end of the 1700s.
I think she painted the pictures but her brother took the credit as it would have been unseemly for a woman to be a painter.
Sir Joshua Reynolds just popped into my head, perhaps he was a character, which makes me think late 1700s
The denouement involved the protagonist revealing herself to be the artist of a particular work by attacking the picture and scraping off the paint to reveal her signature below.
I listened to it as an audiobook 10 years ago so it's at least that old. So pre-2012.
It was well written, literary fiction I think.
Only one time line, no modern person discovering a painting in the attic and solving a mystery.
The protagonist/her family might have been foreign (Italian?)
I think the audio book was about 14 hours so it was quite long...