Looking for artist attributions and sitter identity

A new submission to the queries board as follows:
I am trying to find some help with a portrait I came across about two years ago. This oil on canvas has a plate at the bottom that reads, ‘Lady Fitzgerald, Thomas Gainsborough’. Hugh Belsey later ruled out this being the artist and suggested maybe it be a work by Johann Zoffany. Is this really Emily Fitgerald?
Any ideas very welcome, please use the comments box below.
Comments
The Fitzgerald’s were in Carton House and Kildare House at the dates shown on the portrait label. She may have been Duchess of Leinster?
Liam,
Thank you for your response. I will do some research on that.