This is her article in thepeerage.com, "Hon. Gertrude Leveson-Gower was born on 15 February 1715. She married Lt.-Gen. John Russell, 4th Duke of Bedford, son of Wriothesley Russell, 2nd Duke of Bedford and Elizabeth Howland, on 2 April 1737. She died on 1 July 1794 at age 79. She was buried on 7 July 1794 at Chenies, Buckinghamshire, England. Her will was probated in July 1794.
She was the daughter of John Leveson-Gower, 1st Earl Gower and Lady Evelyn Pierrepont. As a result of her marriage, Hon. Gertrude Leveson-Gower was styled as Duchess of Bedford on 2 April 1737. From 2 April 1737, her married name became Russell."