Brudenell was the subject of The Toast, a scandalous poem written and published in 1732 by the Oxford don William King.
Prior to writing The Toast, King had lost a legal battle in Ireland to Brudenell over a large sum of money he claimed she owed him.
In revenge, he satirised her in the poem as a promiscuous bisexual witch and lesbian named Myra who ruled over a group of sexually uninhibited women in Dublin.
The poem is recognised as one of the earliest uses of the word ‘lesbian’ to describe sexual orientation in English print, although King’s use of it for Brudenell appears to have been unfounded. She was married twice and had 10 children.
Found in Ireland
The 4ft 2in x 3ft 4in (1.27 x 1.02m) portrait in oils, which was painted in c.1692-94 by the Swedish artist Michael Dahl (1659-1743), was found in Ireland by Peter Harrison Fine Art covered with a thick layer of dark varnish.
It is for sale with an asking price of £30,000.