William IV was the third son of George III and the brother of George IV.
At the age of 13, William became a midshipman and began a career in the Royal Navy. In 1789, he was made Duke of Clarence. He retired from the Navy in 1790.
Between 1791 and 1811 he lived with his mistress, the actress Mrs Jordan, and the growing family of their children known as the Fitzclarences. William married Princess Adelaide of Saxe-Meiningen in 1818, but their children died in infancy.
William became heir presumptive at the age of 61, when his second brother, Frederick, Duke of York, died in January 1827.
William's reign (reigned 1830-37) was dominated by the Reform crisis, beginning almost immediately when the Duke of Wellington's Tory government (which William supported) lost the general election in August 1830.
Pledged to parliamentary reform, Earl Grey's Whig government won a further election which William had to call in 1831 and then pushed through a reform bill against the opposition of the Tories and the House of Lords, using the threat of the creation of 50 or more peers to do so.
The failure of the Tories to form an alternative government in 1832 meant that William had to sign the Great Reform Bill. Control of peerages had been used as a party weapon, and the royal prerogative had been damaged.
The Reform Bill abolished some of the worst abuses of the electoral system (for example, representation for so called 'rotten boroughs', which had long ceased to be of any importance, was stopped, and new industrial towns obtained representation).
The Reform Act also introduced standardised rules for the franchise (different boroughs had previously had varying franchise rules) and, by extending the franchise to the middle classes, greatly increased the role of public opinion in the political process.
William understood the theory of the more limited monarchy, once saying 'I have my view of things, and I tell them to my ministers. If they do not adopt them, I cannot help it. I have done my duty.'
William died on 20 June 1837, only a month after his niece, Victoria, had come of age, thus avoiding another regency.