Prince William Henry, the future William IV, was born in London on 21 August 1765. He was the third son of George III and Queen Charlotte and was not expected to become king.

William instead entered the Royal Navy as a teenager. He served as a midshipman and spent time in North America and the Caribbean before leaving active naval service. In 1789 he was created Duke of Clarence.

Between 1791 and 1811 William lived with the actress Dorothea Jordan. They had ten children, who took the surname FitzClarence, but as they were illegitimate, they had no claim to the throne.

William married Princess Adelaide of Saxe-Meiningen in 1818. Their children died in infancy. His elder brother George had one legitimate child, Princess Charlotte, but she died in 1817. Another brother, Frederick, Duke of York, died without children in 1827.

William therefore became heir presumptive to George IV. When George died on 26 June 1830, the third son born 64 years earlier became William IV.

His reign soon became dominated by parliamentary reform. Earl Grey’s Whig government sought to change an electoral system that left growing industrial towns poorly represented, and small ‘rotten boroughs’ continued to return MPs.

The struggle over the Reform Bill placed William in a difficult constitutional position. He dissolved Parliament in 1831 at Grey’s request. He later agreed to create additional peers if necessary to overcome resistance in the House of Lords. The threat was enough. The Reform Act received royal assent on 7 June 1832.

William remained king until his death on 20 June 1837. He had no surviving legitimate child, so the British Crown passed to his niece, the eighteen-year-old Victoria.