William Lamb was born into an aristocratic Whig family in London in 1779, son of Penistone and Elizabeth Lamb. His paternity was always questioned, and it is possible that he was the son of Lord Egremont.

He was educated at Eton College and Trinity College, Cambridge. He then studied the law at Lincoln’s Inn and was called to the bar in 1804. He served as an officer in the Hertfordshire Volunteer Infantry.

In 1807, he was elected to the House of Commons in the Irish seat of Portarlington. He did not distinguish himself in the House, and what reputation he did have was for detachment and indecisiveness. But he did achieve a level of fame when, in 1812, his wife, Caroline Lamb, had a well-publicised affair with Lord Byron (whom she described as “mad, bad, and dangerous to know”).  The scandal had become the talk of Regency Britain, and William was humiliated. He withdrew from politics for four years.

Lamb chose to return to Parliament in 1816, winning the seat of Peterborough (which he exchanged for Hertfordshire in 1819). But his political career failed to develop any momentum. In 1826, he was challenged for his constituency (previously having run alone), and, after finding campaigning to his distaste, resigned.

But in 1827 came a stroke of luck. Lord Liverpool resigned, and Canning was appointed Prime Minister. He was severely lacking in people willing to join his Cabinet, and appointed Lamb to be his Chief Secretary for Ireland. A pocket borough was also provided, sparing Lamb the indignity of having to campaign for his seat. Lamb served in the position under Canning, Goderich, and Wellington, gaining valuable political and administrative experience. In 1828, the death of the elderly Viscount Melbourne would bestow the title, and hereditary peerage, from which point Lamb became Lord Melbourne.

When Lord Grey became Prime Minister in 1830, he sought a mix of Canningites and Whigs, and asked Melbourne, no doubt thinking of his experience dealing with Ireland, to be Home Secretary. During the struggle over the Great Reform Bill, Melbourne seems to have largely stuck to duty, enforcing order – though not with the severity that many Tory peers requested. Though he supported the Reform due to necessity, it clashed with his innate belief in aristocratic leadership, and he refused to countenance increasing the number of peers to ensure the legislation’s passage through the Lords. He was also opposed to Grey’s policy of the abolition of slavery.

When Grey resigned in July 1834, King William IV wanted a Tory, but the mathematics of the House of Commons made that impossible. So, he selected Melbourne, who, by then, had a solid reputation as a conservative Whig. Allegedly, Melbourne only accepted William’s invitation when his secretary remarked ‘such a position never was occupied by a Greek or Roman and, if it lasts only two months, it is well worth to have been Prime Minister of England’.

The government did not last for very long. William IV dismissed it in November, appointing Robert Peel Prime Minister. Nor did this arrangement last long either, with Peel’s Conservatives defeated in the election at the beginning of 1835, leading to Melbourne’s return.

Melbourne’s government was an administrative one. In keeping with Melbourne’s fundamental conservatism there were no bold policy initiatives nor attempts at major reform.

His most important legacy came from his close relationship with the young Queen Victoria, who ascended to the throne on 20 June 1837.  For the next three years, Melbourne essentially tutored Victoria, who had had little political education. Indeed, he was dedicated to this task, that he began to neglect his own government, with an unsupervised Lord Palmerston nearly provoking war with France in 1840. Victoria liked Melbourne’s company, and, due to the ‘Bedchamber Crisis’ of 1839, was able to ensure that he remained Prime Minister for two more years. Only in 1840, when she married Prince Albert of Saxe-Coburg and Gotha, did Melbourne’s importance to her wane, though not before he had talked her out of making Albert ‘King Consort’.

By 1841, the government was divided and drifting. It was defeated on a confidence vote by a single vote in June 1841 and an election was called. In 1841, Melbourne’s Whigs were defeated by Sir Robert Peel’s Conservatives at the general election and, after a second confidence vote, in which he was heavily defeated, Melbourne left power.

In 1805, Lamb married Caroline Ponsonby. They had three children, but only one survived childbirth. Neither party was faithful. Lady Caroline Lamb became known for her affair with Lord Byron. The Lambs formally separated in 1825, though an increasingly unwell Caroline continued to live at Brocket Hall, and William was at her bedside when she died in 1828.

During his premiership, Melbourne was also accused of having an affair with the society figure Caroline Norton, and her husband attempted blackmail. Melbourne considered resignation, but had the support of the King and the Duke of Wellington, and was able to continue.

Lord Melbourne died in 1848.

The city of Melbourne, the second most populous in Australia, is named after Lord Melbourne.