Several scholars write about speculation that Mrs Quentin (known as Georgina and sometimes Harriet) was the inspiration for Jane Bennet.
Jocelyn Harris’s book Satire, Celebrity, & Politics in Jane Austen (Bucknell University Press, 2017) is a great starting point for more information on this story. As well as Mrs Quentin, Harris also suggests another of George IVs mistresses as a possible reference for Jane Bennet.
There are many reviews of the book online too.
You can find the William Blake etching of Georgina (also known as Harriet) Quentin in the British Museum.
Read about Georgiana/Harriet Quentin in Memoirs of the Life of the Celebrated Mrs Q.
Read Jane’s letter to Cassandra (24 May 1815, letter No:44 or XLIV) at eg gutenberg.com or pemberley.com