"Margaret Georgiana Spencer, Countess Spencer (née Poyntz; 8 May 1737 – 18 March 1814), was an English philanthropist. She was born at St James's Palace as the daughter of a diplomat and a maid of honour to Caroline of Ansbach. In 1754, she married John Spencer, one of the wealthiest men of the era. A love match, the marriage resulted in the births of three surviving children, who included Georgiana Cavendish, Duchess of Devonshire. The Spencers became earl and countess in 1765, a reward granted by the Duke of Newcastle for John's political loyalty to the Whig party.
Lady Spencer was a noted philanthropist, and was in communication with a large network of charitable organisations. Her correspondence with a friend represents the largest private collection of letters in the British Library. Lord and Lady Spencer were generous patrons, and frequently hosted plays and concerts at their London estate, Spencer House, which they built in 1764." - (Wikipedia (en) 23.12.2020)