UK Prime Ministers Ranked by IQ: The Only Estimates, Degrees and Expert Rankings

Search for the IQ of UK prime ministers and you will find ranked lists, with Winston Churchill, Margaret Thatcher and Boris Johnson near the top and a number beside every name. No British prime minister has a published IQ test score, and we found no study that estimates IQ for British prime ministers the way one famous paper did for American presidents. This article sets out what does exist: one 1926 set of estimates for six historic prime ministers, the degree classes of the modern ones, and the expert rankings of who did the job best. It also explains why none of the three can be turned into a ranking of UK prime ministers by IQ.

Is there an IQ ranking of UK prime ministers?

Not a trustworthy one. For US presidents there is a peer-reviewed paper, Simonton's 2006 study in Political Psychology, which our US presidents ranked by IQ article walks through. We looked for a British equivalent in Crossref (eight query wordings), OpenAlex (eight) and Europe PMC (two), plus a dozen web searches, and every IQ-and-leaders hit was about American presidents or about children and medicine. The British writing on prime ministers is political science: biographies, and surveys that rate performance.

That leaves the lists. A ranking that gives every prime minister from Walpole to the present an IQ is not drawing on a published test or study, and we could not trace any of the figures that circulate for modern prime ministers to a source. The ranges on our own profiles are our estimates, stated as such: Winston Churchill 140 to 160, Margaret Thatcher 135 to 150 and Boris Johnson 125 to 140. Each is built from the academic and career record, none from a test, and our guide to where celebrity IQ numbers come from explains the difference.

The only IQ numbers for British prime ministers: Cox, 1926

Catharine Cox's Genetic Studies of Genius (Stanford University Press, 1926) estimated the childhood and youth IQ of 301 eminent people born between 1450 and 1850, by scoring what the surviving records say they did young. It is the same study that sits under eight of the US presidential figures. Six of her 301 were British prime ministers: Robert Walpole, William Pitt the Elder, William Pitt the Younger, George Canning, Robert Peel and Benjamin Disraeli. She gave each two estimates, one from the record to about age 17 and one to about age 26, and then corrected both for how complete the record was. The corrected values, from her fold-out Table 12A, are below, ranked by the mean of the two:

• 1. William Pitt the Younger: 170 and 190 (mean 180)
• 2. Robert Peel: 170 and 180 (mean 175)
• 3. Benjamin Disraeli: 160 and 165 (mean 162.5)
• 4. George Canning: 155 and 165 (mean 160)
• 5. William Pitt the Elder: 155 and 155 (mean 155)
• 6. Robert Walpole: 145 and 155 (mean 150)

Before correction her case-summary headers read Pitt the Younger 160 and 180, Peel 155 and 170, Disraeli 145 and 150, Canning 150 and 155, Pitt the Elder 140 and 140 and Walpole 125 and 130, so the two sets should never be mixed in one table. Several names that often turn up in such lists are not Cox subjects: we found Gladstone only in a bibliography, and Wellington, Palmerston and Melbourne have no case study. No prime minister born after 1850 can appear, because her sample stops there. That rules out every one of the modern prime ministers.

What the numbers rest on matters. Of Peel, Cox writes that he "took the B.A. degree at Oxford with double first-class honors", and that precocity drives his 170 and 180. Walpole sits last because the record of his youth is thin; her own case summary lists no production or achievement for him. These are mental-age-era estimates of men known for their later achievements, with a reliability that she put at about .43 for Walpole's data and about .75 for Peel's. Read them as a ranking of how well documented and how early-bright a record was, not as test scores. Our note on ratio and deviation IQ explains why a 1926 figure is not on the modern scale.

Prime ministers' degrees: first, second or none

Degree class is the most checkable proxy, and the one people reach for when they say a prime minister "must be clever". It is a weak one: a first-class degree reflects one set of examinations at one age, in one subject. For the 19 prime ministers from Clement Attlee to Andy Burnham, who took office on 20 July 2026 according to gov.uk, the classes in their published biographies are:

• First-class degree (5): Anthony Eden (Oriental languages, Oxford, a Double First), Harold Wilson (PPE, Oxford), Gordon Brown (history, Edinburgh), David Cameron (PPE, Oxford), Rishi Sunak (PPE, Oxford)
• Second-class degree (8): Clement Attlee, Edward Heath, Margaret Thatcher (chemistry), Tony Blair (jurisprudence), Theresa May (geography), Boris Johnson (classics, upper second), Liz Truss (PPE, reported as a 2:1) and Andy Burnham (English at Cambridge, upper second)
• Third-class degree (1): Alec Douglas-Home (modern history, Oxford)
• No degree (3): Winston Churchill, James Callaghan, John Major
• Left before finals (1): Harold Macmillan took a first in Honour Moderations in 1914 and did not return to complete his degree
• Class not confirmed (1): Keir Starmer, who graduated in law from Leeds in 1985 and took the Bachelor of Civil Law at Oxford in 1986

Most of these classes come from each prime minister's own biography page, so treat them as reported rather than audited: we could not open a second source for several, and for Truss we found one. A count of first-class degrees across every prime minister back to Walpole does not exist in any reliable source we could read. The counts we did find disagree because they count differently. Wikipedia's list, as of July 2026, says that of 59 prime ministers 31 were educated at Oxford, 15 at Cambridge and 20 at Eton. The Sutton Trust, in July 2024, counted 55 heads of government and found 28 at Oxford, 19 at Eton and 13 at both. Our pieces on the average IQ of Oxford students and on Oxford's admissions test show how little an elite place says about a single score.

Do cleverer prime ministers rank higher? What the expert surveys show

Academics do rank prime ministers, and their results can be set beside the degrees. The 2004 survey by MORI and the University of Leeds asked 258 academics to rate the 20 prime ministers of the twentieth century from 0 to 10, and 139 answered in full. Attlee came first with 8.34, Churchill second with 7.88, Lloyd George third with 7.33, Thatcher fourth with 7.14, Macmillan fifth with 6.49 and Blair sixth with 6.30. Eden finished last with 2.53. Here are the 11 post-war prime ministers in that survey, with the degree each took:

• 1st Attlee (8.34): second-class degree
• 2nd Churchill (7.88): no degree
• 4th Thatcher (7.14): second-class degree
• 5th Macmillan (6.49): first in Moderations, no final degree
• 6th Blair (6.30): second-class degree
• 9th Wilson (5.93): first-class degree
• 12th Callaghan (4.75): no degree
• 13th Heath (4.36): second-class degree
• 15th Major (3.67): no degree
• 19th Douglas-Home (3.33): third-class degree
• 20th Eden (2.53): Double First

There is no pattern a reader could use. The prime minister with the Double First was rated worst, the one rated best had a second, and the second-best had no degree at all. A 2021 survey by Leeds and Woodnewton, answered by 93 academics at 44 universities between 1 and 16 June 2021, again put Attlee first, Thatcher second and Blair third among the post-war prime ministers, with Theresa May level with Eden at the bottom. Surveys of MPs by Royal Holloway in 2013 (158 MPs, a 24 per cent response) and 2023 gave the same top four, Thatcher, Attlee, Blair and Churchill, in both years. These surveys rate success in office. None of them measures intelligence, and we found no source that links rated success to IQ for British prime ministers.

What about Churchill, Thatcher and Boris Johnson?

Churchill is the clearest case of a school record read the wrong way. He passed the Harrow entrance examination in April 1888, at 13, and failed to get into Sandhurst twice before passing on the third attempt in 1893; the International Churchill Society says he then finished near the top of his class. He never went to university, and he was born in 1874, so Cox's sample could not include him. Thatcher took a second-class chemistry degree at Oxford in 1947 and later qualified as a barrister. Johnson won a scholarship to Eton and another to Balliol, and left with an upper second. None has a published test score, and the 79 that some searches attach to Johnson has no source we could find.

Britain has also been measured as a place rather than a person: our smartest places in the UK study ranks regions, not leaders. For a sense of what the figures mean on the normal curve, our IQ percentile calculator converts any score to a rank, and the leader IQ article covers what the research says about leaders and ability. The global version of this question, covering leaders from the United States to Japan, is in world leaders ranked by IQ, and the American counterpart for the Founders is Founding Fathers ranked by IQ.

How to read any "UK prime ministers IQ" list

• Does it name a test and a year? A prime minister's IQ number with neither is repeating something.
• Is the number a range? Honest estimates are ranges, and Cox's two figures per person show how much a single estimate moves.
• Does it cover every prime minister with the same method? No method covers Walpole and Starmer alike.
• Does it say which scale it is on? Cox's 1926 estimates sit on the old mental-age scale and are not comparable with a modern score, where the average is 100.

The bottom line: an honest "UK prime ministers ranked by IQ" has two parts. For six historic prime ministers there are Cox's 1926 estimates, led by Pitt the Younger and Peel, which are records scored by a researcher. For everyone since Attlee there is no IQ number at all, only degrees and ratings of success that point in different directions. To place a measured score of your own, take the IQ Metrics IQ test and read the result against the bell curve.

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