Philosophy, Politics and Economics (PPE) is an interdisciplinary undergraduate/post-graduate degree which combines study from three disciplines. The first institution to offer degrees in PPE was the University of Oxford in the 1920s. This particular course has produced a significant number of notable graduates such as Bill Clinton, the 42nd President of the United States (who left before completing his degree); Christopher Hitchens, the British–American author, polemicist, debater, and journalist; David Cameron, the former Prime Minister of the United Kingdom; Ed Miliband, the former Leader of the Opposition; and Tony Abbott, the former Prime Minister of Australia.