Maria, Duchess of Gloucester and Edinburgh (née Maria Walpole; 10 July 1736 – 22 August 1807) was Countess Waldegrave from 1759 to 1766 as the wife and then widow of James Waldegrave, 2nd Earl Waldegrave, and a member of the British royal family from 1766 as the wife and then widow of Prince William Henry, Duke of Gloucester and Edinburgh. Early life Maria Walpole was the illegitimate daughter of Sir Edward Walpole and Dorothy Clement. Her grandfather was Robert Walpole, Earl of Orford, considered to be the first Prime Minister of the United Kingdom (1721–41). She grew up at Frogmore House in Windsor, but her parents were not married, and her illegitimate status hindered her social standing despite her family connections. Countess Waldegrave On 15 May 1759, she married James Waldegrave, 2nd Earl Waldegrave at the house in Pall Mall of her father, Sir Edward Walpole. The ceremony was performed by Frederick Keppel, the future Bishop of Exeter, and the official witnesses were Sir Edward and his brother, Horace Walpole. The Earl Waldegrave died on 28 April 1763. They had three children: Lady Elizabeth Waldegrave (1760–1816) who married her paternal first cousin the 4th Earl Waldegrave. Three sons became Earls Waldegrave and all succeeding earls are descended from this marriage. Lady Charlotte Waldegrave (1761–1808) who married the future 4th Duke of Grafton. All succeeding Dukes of Grafton are descended from this marriage. Lady Anne Horatia Waldegrave (1762–1801) who married Lord Hugh Seymour, son of the 1st Marquess of Hertford. Anna's and Hugh's descendants include Charles Spencer, 6th Earl Spencer; Diana, Princess of Wales; William, Prince of Wales and Prince Harry, Duke of Sussex. Prior to her marriage, she was perhaps secretly engaged to be married to Robert Bertie, 4th Duke of Ancaster (1756–1779), as she is said by her uncle Horace Walpole and others to have put on mourning for the dissolute young Duke. There is a portrait of Maria in 1764–65, shortly after she was widowed, painted by Sir Joshua Reynolds, in the Dunedin Public Art Gallery. She also commissioned him in 1780 to paint The Ladies Waldegrave, a group portrait of her and Waldegrave's three daughters. Duchess of Gloucester On 6 September 1766 she married Prince William Henry, Duke of Gloucester and Edinburgh, at her home in Pall Mall, London. The Duke was a brother of King George III. The marriage was conducted in secret as the British