This itsy-bitsy image is all that's available of an accomplished artist, her work already posted here, with this partial biography from unofficial royalty.com: "...Lady Diana married Frederick St John, 2nd Viscount Bolingbroke in 1757 and was Lady of the Bedchamber to Queen Charlotte, wife of King George III, from 1762-1768. The marriage, which produced two children, was an unhappy one and in 1768, Lord Bolingbroke petitioned Parliament for a divorce. Neither Lady Diana nor Lord Bolingbroke had been faithful during their marriage. Shortly after Parliament approved the divorce, Lady Diana married Topham Beauclerk, the only son of Lord Sidney Beauclerk and a great grandson of King Charles II. The couple had four children, three of which were born before they married.
Lady Diana, the original “Lady Di,” was in a stellar circle of friends which included Georgiana Cavendish (Duchess of Devonshire, who was born Georgiana Spencer, the eldest daughter of John Spencer, 1st Earl Spencer), writer Samuel Johnson, historian Edward Gibbon, actor David Garrick, statesman Charles Fox, writer James Boswell, statesman Edmund Burke, and art historian/politician Horace Walpole. She survived her second husband by 28 years and died in Twickenham, Surrey, England in 1808 at age 74."
From Wikimedia; image resized to 17.57 cm at 28.35 pixels/cm.