William IV becomes king of Britain and Hanover following the death without surviving legitimate issue of his older brother George IV.

William IV was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 26 June 1830 until his death in 1837. The third son of George III, William succeeded his elder brother George IV, becoming the last king and penultimate monarch of Britain's House of Hanover.

George IV was King of the United Kingdom of Great Britain and Ireland and King of Hanover from 29 January 1820 until his death in 1830. At the time of his accession to the throne, he was acting as prince regent for his father, King George III, having done so since 5 February 1811 during his father's final mental illness.