In what year were the parents of Prince Octavius of Great Britain married?  
Prince Octavius of Great Britain: Prince Octavius (23 February 1779 – 3 May 1783) was the 13th child and 8th son of King George III and his queen consort Charlotte of Mecklenburg-Strelitz. Charlotte of Mecklenburg-Strelitz: Charlotte of Mecklenburg-Strelitz (Sophia Charlotte; 19 May 1744 – 17 November 1818) was by marriage to King George III the Queen of Great Britain and Ireland from her wedding in 1761 until the union of the two kingdoms in 1801, after which she was Queen of the United Kingdom of Great Britain and Ireland until her death in 1818.
1761