Background
Williams-Wynn was born in Llanforda, Oswestry. She was the eldest child of the Prime Minister George Grenville and his wife Elizabeth, daughter of the Tory statesman Sir William Wyndham, Bt, and she was related to the two Prime Minister William Pitts through her paternal aunt Hester Grenville who married Pitt the Elder (the 1st Earl of Chatham) and became mother of William Pitt the Younger.