List of Old Etonian Prime Ministers

Of the 52 British prime ministers since Walpole, 18 (including David Cameron) were educated at Eton. That's more than 1 in 3.

1. Robert Walpole 1721-1742
2. John Stuart, 3rd Earl of Bute 1762–1763
3. William Pitt the Elder, 1st Earl of Chatham 1766-1768
4. Frederick North, 2nd Earl of Guildford 1770–1782
5. William Grenville 1806–1807
6. George Canning 1827
7. Arthur Wellesley, 1st Duke of Wellington 1828–1830 & 1834
8. Charles Grey, 2nd Earl Grey 1830–1834
9. William Lamb, 2nd Viscount Melbourne 1834 & 1835–1841
10. Edward Smith-Stanley, 14th Earl of Derby 1852, 1858–1859 & 1866–1868
11. William Gladstone 1868–1874, 1880–1885, 1886 & 1892–1894
12. Robert Cecil, 3rd Marquess of Salisbury 1885–1886, 1886–1892 & 1895–1902
13. Archibald Primrose, 5th Earl of Rosebery 1894–1895
14. Arthur Balfour, 1st Earl of Balfour 1902-1905
15. Anthony Eden 1955–1957
16. Harold Macmillan, 1st Earl of Stockton 1957–1963
17. Alec Douglas-Home 1963-1964
18. David Cameron 2010-

UPDATE: a nickcleggsfault visitor enquires if Nick Clegg also attended Eton College. The answer is no. He attended Westminster School.