Princess Mary Adelaide of Cambridge (November 27, 1833 - October 27, 1897), was the younger daughter of Prince Adolphus, 1st Duke of Cambridge, the seventh son of King George III of the United Kingdom, and his wife, Princess Augusta of Hesse-Cassel. She was a first cousin of Queen Victoria and is mainly remembered as the mother of Queen Mary. She was one of the first members of the British Royal Family to patronize a wide number of charities.
Her Royal Highness Princess Mary Adelaide Wilhelmina Elizabeth was born in Hanover, Germany, where her father had served as governor-general in place of his brothers, King George IV and later King William IV. Nicknamed "Fat Mary" because of her enormous girth, the princess had extravagant tastes in clothes, food, and jewels, but little income or marriage prospects.
On June 12, 1866, she married His Serene Highness Prince Francis of Teck, later Duke of Teck (August 28, 1837-January 21, 1900) at Kew Church, Surrey. While Princess Mary Adelaide was a British princess of the blood royal and retained her qualification of Royal Highness, her husband, as the product of a morganatic marriage between Duke Alexander of Württemberg and Countess Claudine Rhédey von Kis-Rhéde, was only a Serene Highness. He was granted the qualification of "Highness" by Queen Victoria on July 11, 1887.
The Duke and Duchess of Teck had four children:
- HSH Princess Victoria Mary of Teck (Victoria Mary Augusta Luisa Olga Pauline Claudine Agnes)
- HSH Prince Adolphus (Adolphus Alexander Albert Edward George Philip Ladislaus) August 13, 1868-October 24, 1927, 2nd Duke of Teck (in the Kingdom of Württemberg); created 1st Marquess of Cambridge, July 16, 1917.
- HSH Prince Francis of Teck (Francis Joseph Leopld Frederick) January 9, 1870-October 22, 1910.
- HSH Prince Alexander of Teck (Alexander Augustus Frederick William George) April 14, 1874-January 16, 1957, created 1st Earl of Athlone