Princess Mary, Duchess of Gloucester and Edinburgh was the eleventh child and fourth daughter of King George III and his consort Charlotte of Mecklenburg-Strelitz.

Charlotte of Mecklenburg-Strelitz was Queen of Great Britain and Ireland as the wife of King George III from their marriage on 8 September 1761 until her death in 1818. The Acts of Union 1800 unified Great Britain and Ireland into the United Kingdom of Great Britain and Ireland. As George's wife, she was also Electress of Hanover until becoming Queen of Hanover on 12 October 1814. Charlotte was Britain's longest-serving queen consort, serving for 57 years and 70 days.