The office of Prime (or ‘first’) Minister developed in the eighteenth century, when the First Lord of the Treasury came to be regarded as the official head of the government. The first person who is generally regarded as having acted as Prime Minister was Sir Robert Walpole.
| Sir Robert Walpole | 1721–1742 | Whig |
| Spencer Compton, Earl of Wilmington | 1742–1743 | Whig |
| Henry Pelham | 1743–1754 | Whig |
| Thomas Pelham-Holles, Duke of Newcastle | 1754–1756 | Whig |
| William Cavendish, Duke of Devonshire | 1756–1757 | Whig |
| Thomas Pelham-Holles, Duke of Newcastle | 1757–1762 | Whig |
| John Stuart, Earl of Bute | 1762–1763 | Tory |
| George Grenville | 1763–1765 | Whig |
| Charles Watson-Wentworth, Marquess of Rockingham | 1765–1766 | Whig |
| William Pitt, Earl of Chatham | 1766–1768 | Whig |
| Augustus Fitzroy, Duke of Grafton | 1768–1770 | Whig |
| Frederick North, Lord North | 1770–1782 | Tory |
| Charles Watson-Wentworth, Marquess of Rockingham | 1782 | Whig |
| William Petty-Fitzmaurice, Earl of Shelburne | 1782–1783 | Whig |
| William Cavendish-Bentinck, Duke of Portland | 1783 | Whig–Tory coalition |
| William Pitt (the Younger) | 1783–1801 | Tory |
| Henry Addington1801–1804 | Tory | |
| William Pitt (the Younger) | 1804–1806 | Tory |
| William Wyndham Grenville, Lord Grenville | 1806–1807 | Whig–Tory coalition (The Ministry of All the Talents) |
| William Cavendish-Bentinck, Duke of Portland | 1807–1809 | Tory |
| Spencer Perceval1 | 809–1812 | Tory (assassinated) |
| Robert Jenkinson, Lord Liverpool | 1812–1827 | Tory |
| George Canning | 1827 | Tory |
| Frederick John Robinson, Lord Goderich | 1827–1828 | Tory |
| Arthur Wellesley, Duke of Wellington | 1828–1830 | Tory |
| Charles Grey, Earl Grey | 1830–1834 | Whig |
| William Lamb, Viscount Melbourne | 1834 | Whig |
| Arthur Wellesley, Duke of Wellington | 1834 | Tory |
| Sir Robert Peel | 1834–1835 | Tory–Conservative |
| William Lamb, Viscount Melbourne | 1835–1841 | Whig |
| Sir Robert Peel | 1841–1846 | Tory–Conservative |
| Lord John Russell | 1846–1852 | Whig |
| Edward Smith-Stanley, Earl of Derby | 1852 | Tory–Conservative |
| George Hamilton-Gordon, Earl of Aberdeen | 1852–1855 | Whig |
| Henry John Temple, Viscount Palmerston | 1855–1858 | Whig |
| Edward Smith-Stanley, Earl of Derby | 1858–1859 | Tory–Conservative |
| Henry John Temple, Viscount Palmerston | 1858–1865 | Whig |
| John Russell, Earl Russell | 1865–1866 | Whig–Liberal |
| Edward Smith-Stanley, Earl of Derby | 1866–1868 | Tory–Conservative |
| Benjamin Disraeli | 1868 | Conservative |
| William Ewart Gladstone | 1868–1874 | Liberal |
| Benjamin Disraeli (Earl of Beaconsfield from 1876) | 1874–1880 | Conservative |
| William Ewart Gladstone | 1880–1885 | Liberal |
| Robert Gascoyne-Cecil, Marquess of Salisbury | 1885–1886 | Conservative |
| William Ewart Gladstone | 1886 | Liberal |
| Robert Gascoyne-Cecil, Marquess of Salisbury | 1886–1892 | Conservative |
| William Ewart Gladstone | 1892–1894 | Liberal |
| Archibald Primrose, Earl of Rosebery | 1894–1895 | Liberal |
| Robert Gascoyne-Cecil, Marquess of Salisbury | 1895–1902 | Conservative |
| Arthur Balfour | 1902–1905 | Conservative |
| Sir Henry Campbell-Bannerman | 1905–1908 | Liberal |
| Herbert Henry Asquith | 1908–1916 | Liberal |
| David Lloyd George | 1916–1922 | Liberal–Conservative coalition |
| Andrew Bonar Law | 1922–1923 | Conservative |
| Stanley Baldwin | 1922–1924 | Conservative |
| James Ramsay MacDonald | 1924 | Labour |
| Stanley Baldwin | 1924–1929 | Conservative |
| James Ramsay MacDonald | 1929–1931 | Labour |
| James Ramsay MacDonald | 1931–1935 | National Government (Labour–Conservative–Liberal coalition) |
| Stanley Baldwin | 1935–1937 | National Government (Conservative–Liberal) |
| Neville Chamberlain | 1937–1940 | National Government |
| Winston Spencer Churchill | 1940–1945 | Coalition (Conservative–Labour–Liberal) |
| Clement Attlee | 1945–1951 | Labour |
| Winston Spencer Churchill | 1951–1955 | Conservative |
| Anthony Eden | 1955–1957 | Conservative |
| Harold Macmillan | 1957–1963 | Conservative |
| Sir Alec Douglas-Home | 1963–1964 | Conservative |
| Harold Wilson | 1964–1970 | Labour |
| Edward Heath | 1970–1974 | Conservative |
| Harold Wilson | 1974–1976 | Labour |
| James Callaghan | 1976–1979 | Labour |
| Margaret Thatcher | 1979–1990 | Conservative |
| John Major | 1990–1997 | Conservative |
| Anthony (Tony) Blair | 1997–2007 | Labour |
| Gordon Brown | 2007–2010 | Labour |
| David Cameron | 2010– | Coalition (Conservative–Liberal Democrat) |