Henrietta Ponsonby, Countess of Bessborough (known as Harriet) was the sister of Georgiana, Duchess of Devonshire. She married Frederick Ponsonby in 1780, the future Earl of Bessborough and the 5th Duke of Devonshire’s cousin. She was devoted to her sister and assisted with her political campaigning. With her husband, Harriet was also deeply involved in the Devonshire House circle, falling into significant amounts of debt.
The marriage was not a happy one, and after a series of affairs (including one with the playwright Richard Sheridan) Harriet met Lord Granville Leveson-Gower while abroad, on the same trip designed to take Georgiana overseas after the Duke of Devonshire discovered her pregnancy by Charles Grey.
Harriet and Leveson-Gower embarked on a seventeen-year affair that produced two illegitimate children. Harriet also had four children with her husband, including her daughter Lady Caroline Lamb, the famous novelist.
The affair only ended when Leveson-Gower married Harriet’s niece (and Georgiana’s daughter), Lady Henrietta Cavendish. Historians have debated the extent to which Harriet had a hand in this arrangement and the motivations behind her actions, as well as the long-term effects on her.
After a lifetime embroiled in high society and its many intrigues, she spent her later years in the company of familiar friends, children, and grandchildren. She died in 1821 and was buried in the Cavendish vault at All Saints, Derby.
Main image: Henrietta Frances ('Harriet') Ponsonby (née Spencer), Countess of Bessborough by Joseph Grozer, after Sir Joshua Reynolds, mezzotint, published 1786 NPG D31727 © National Portrait Gallery, London
