Skip to main content
Margaret Thatcher giving a speech in 1991

The 7 longest serving British Prime Ministers

Margaret Thatcher was the seventh-longest running Prime Minister | Image: David Fowler /

It was in April 1721 that the person who would become the longest serving British Prime Minister took office. Who was he, and who have been some of the other PMs to enjoy long tenures in the top job?

7th longest serving: Margaret Thatcher:

Time in office: 11 Years, 208 Days

As well as being Prime Minister for longer than anyone else in the 20th Century, Margaret Thatcher was also the most controversial figure to hold the post. Adored and despised in equal measure, she was hailed by many as a fierce champion of free-market capitalism, credited with putting Britain back on the path to prosperity after the economic unease of the late 1970s. However, her time in Number 10 – which sprawled from 1979 to 1990 – was marked by domestic strife, with the mass closure of mines leading to bitter protests and to Thatcher describing striking miners as the 'enemy within'. The Falklands War and the Brighton hotel bombing, when Thatcher narrowly escaped being killed in a devastating IRA attack which killed five others, were among the dramatic chapters in a premiership that still arouses heated debate today.

6th longest serving: Frederick North

Time in office: 12 Years, 58 Days

Frederick North, better known as Lord North, was Prime Minister from 1770 to 1782. A political prodigy who became an MP at the tender age of 22, North’s time as PM commenced with his very own Falklands crisis, when Britain nearly came to blows with Spain over the islands. However, it was the American revolution which would later define North’s premiership, with his historical standing forever tarnished by his handling of the situation in the colonies. North reacted to discontent among American colonists by laying down punishing laws known as the Coercive Acts (aka, the Intolerable Acts) which helped trigger the American War of Independence. North would resign after a decisive defeat in the war, leading to his lasting reputation as the 'Prime Minister who lost America'.

5th longest serving: William Gladstone

Time in office: 12 years, 126 days

William Ewart Gladstone was more than just a political leader: he was a colossus of the Victorian age, although Victoria herself wasn’t particularly enamoured, calling him a 'half-mad firebrand'. Gladstone was a fiercely driven campaigner and reformer – one of his abiding causes was home rule for Ireland, and he was even known to walk London’s streets at night to offer help and support to sex workers (he’d previously founded the 'Church Penitentiary Association for the Reclamation of Fallen Women'). Gladstone served four separate terms as Prime Minister between the years of 1868 and 1894, forming his final government at the age of 82. Though he’s an undisputed giant of his time, his reputation has come under criticism more recently because of his family ties to slavery, and his own initial opposition to its abolition.

4th longest serving: Robert Cecil

Time in office: 13 years, 252 days

Better known as the Marquess of Salisbury, he was Prime Minister for three separate terms between the years of 1885 and 1900. A bona fide aristocrat, Salisbury descended from members of Elizabeth I’s court, but despite his lavish background he had an unhappy and withdrawn childhood, preferring books to games and suffering incessant bullying at school. Even as Prime Minister, his aversion to permanent alliances with other nations led to his foreign policy being dubbed 'splendid isolation'. However, he also oversaw imperialistic expansion of the British Empire – particularly in Africa – and the Second Boer War unfolded under his watch. Lord Salisbury remains the last Prime Minister to run the country from the House of Lords.

3rd longest serving: Robert Jenkinson

Time in office: 14 years, 305 days

Robert Jenkinson, the Earl of Liverpool, was in office from 1812 to 1827, ascending to the top job after a tragic event: the first and only assassination of a British Prime Minister. His predecessor, Spencer Perceval, was shot dead in the House of Commons by an embittered merchant, leading to Liverpool commencing his epic tenure as leader of the country. It would be a tumultuous era, featuring titanic events like the War of 1812 with the United States (which saw the White House set on fire) and the final defeat of Napoleon at the Battle of Waterloo. Lord Liverpool also had to deal with an economic slump on the home front, and widespread social unrest. Public calls for political reform led to one of the most shocking events of his tenure: the Peterloo Massacre, when an estimated 18 protestors were killed by private militia in Manchester.

2nd longest serving: William Pitt the Younger

Time in office: 18 years, 343 days

Pitt the Younger more than deserved his moniker: he was a mere 24 years of age when he first became Prime Minister in 1783. He served two separate terms, and has the dubious merit of being the British leader who first introduced income tax to the nation – a much needed revenue injection following costly conflicts like the American War of Independence. It was during his premiership that the Acts of Union 1800 came into force, uniting the Kingdom of Great Britain with the Kingdom of Ireland. Pitt also played an integral role in bringing Britain into a fresh European alliance against Napoleon, but the stresses of power took their toll – he died aged just 46, during his second term as Prime Minister.

Longest serving: Sir Robert Walpole

Time in office: 20 years, 314 days

The man who shaped the office of Prime Minister remains the person who served in that role the longest. Sir Robert Walpole began his premiership in 1721, and carried on for almost 21 years. The job wasn’t yet formalised, having evolved slowly over time, and the term 'prime minister' was originally a term of sardonic abuse, aimed at politicians who sought to rise above their station. Walpole himself famously said 'I unequivocally deny that I am sole and prime minister'. However, Walpole was undoubtedly a pioneeringly powerful figure, cultivating close relations with the new Hanoverian monarchy. An important part of his legacy is 10 Downing Street – he was offered the house as a private residence by George II, but insisted it being given to those who serve as the First Lord of the Treasury. Which, for quite some time now, means the Prime Minister.