Princess Augusta of Cambridge, later the Grand Duchess of Mecklenburg-Strelitz (18 July 1822-5 December 1916), was a member of the British Royal Family. Her father was Prince Adolphus, 1st Duke of Cambridge, the seventh son of King George III and Queen Charlotte, and his wife, Princess Augusta of Hesse-Cassel. Princess Augusta of Cambridge has the distinction of being the longest-lived grandchild of George III, having lived through the reigns of five British Sovereigns.

Her Royal Highness Princess Augusta Caroline Charlotte Elizabeth Mary Sophia Louise of Great Britain and Ireland was born at the Palace of Montbrillant during the time her father, the Duke of Cambridge, was viceroy of Hanover on behalf of his brother, King George IV. Princess Augusta had one brother, Prince George, 2nd Duke of Cambridge; and one sister, Princess Mary Adelaide of Cambridge, later the Duchess of Teck. As such Princess Augusta was a first cousin of Queen Victoria, and aunt to Princess Victoria Mary of Teck, the consort of George V .

On 28 June 1843, Princess Augusta married her first cousin, His Royal Highness Grand Duke Friedrich Wilhelm of Mecklenburg-Strelitz (17 October 1819-20 May1904), at Buckingham Palace. The marriage of the Grand Duke and Grand Duchess produced two children:

  • An unnamed son 1845-1845
  • Prince Adolph Friedrich (22 July 1848-11 June 1914), who succeeded his father as Grand Duke Adolph Friedrich V in May 1904.

Although she spent most her adult life in Germany, the Grand Duchess Augusta retained close personal ties to the British royal family. During the lifetime of her mother, the Duchess of Cambridge, she frequently visited her apartments at Kensington Palace. After her mother's death in 1850, the Grand Duchess acquired a house in London's Buckingham-gate area, where she spent a portion of the year until advanced old age made it impossible for her travel abroad. In making preparations for the coronation of King Edward VII and Queen Alexandra in 1901, the Duke of Norfolk consulted her on matters of ettiquite and attire. She was able to provide details of the coronation of Queen Victoria for which no written records existed. The Grand Duchess of Mecklenburg-Sterlitz was particularly close to her niece, the future Queen Mary. She attended the coronation of King George V (who was her first cousin twice removed) and Queen Mary at Westminster Abbey on 22 June 1911. During World War I, the Swiss embassy passed letters from the Queen to her aunt who still lived in Germany.

The Dowager Grand Duchess of Mecklenburg-Strelitz died at Neustrelitz, where she was buried. As the longest lived grandchild of George III, she was the last link to the British branch of the House of Hanover. At the time of her death, she was 94 years and 70 days old, making her the longest-lived British princess of the blood royal until Princess Alice, Countess of Athlone, a male-line granddaughter of Queen Victoria, broke the record in 1977.