Henrietta Ponsonby; Countess of Bessborough; 1761 ? 1821; born Lady Henrietta Frances Spencer (generally called Harriet); was the wife of Frederick Ponsonby; 3rd Earl of Bessborough and mother of the notorious Lady Caroline Lamb. Her father; John Spencer; 1st Earl Spencer; was a great-grandson of John Churchill; 1st Duke of Marlborough. Her sister was Georgiana Cavendish; Duchess of Devonshire. From The Connoisseur Magazine; published 1902.