|Theresa May. Oxford gets another, to make|
27. Cambridge has 14 British PMs.
The official site counts a Prime Minister twice if he came back after an interim (so far no female Prime Ministers have achieved this). The Disraeli-Gladstone pas de deux leaps to mind.
The Oxford and Cambridge rankings now show, by my calculations, a total of 41 Oxbridge Prime Ministers:
Oxford - 27
Cambridge - 14
[Postscript July 22: These numbers were confirmed in a recent post by the Editor of Oxford Today, Richard Lofthouse. I was pleased to see that two of the comments on his post as of July 22 stepped away from self-congratulation or questions about pre-university testing to ask fellow Oxonians, more or less: "Where did our educational go wrong to produce a Cameron and a Johnson?" (And, by implication, a Brexit.)]
Within Oxford, the leading colleges are:
Christ Church - 13
Balliol - 3
Trinity - 3
Brasenose - 2
Other: Hart Hall (later Hertford), Jesus, Somerville, St Hugh's, St John's, Univ.
Within Cambridge, the leading colleges are:
Trinity - 6
St John's - 4
Other: Clare, King's, Pembroke, Peterhouse.
Other universities attended (10, of which 5 are not in addition to Oxford or Cambridge. I credit two universities when someone attended both; none of the Prime Ministers is listed as attending both Oxford and Cambridge, but five attended a second university in Birmingham, or Scotland, or the Netherlands or Germany):
Edinburgh - 3
Glasgow - 2
Mason Science College (later part of Birmingham) - 2
Leiden - 1
Utrecht - 1
Leipzig, Saxony - 1
No university attended - 8
Summary: Oxford 27, Cambridge 14, Other university (not additional) 5, No university 8.