Boris Johnson, Michael Gove, David Cameron, George Osborne, Theresa May, Dominic Cummings, Daniel Hannan, Jacob Rees-Mogg: Whitehall is swarming with old Oxonians. They debated each other in tutorials, ran against each other in student elections, and attended the same balls and black tie dinners.

They aren't just colleagues - they are peers, rivals, friends. And, when they walked out of the world of student debates onto the national stage, they brought their university politics with them.

Eleven of the fifteen postwar British prime ministers went to Oxford. In Chums, Simon Kuper traces how the rarefied and privileged atmosphere of this narrowest of talent pools - and the friendships and worldviews it created - shaped modern Britain.