Complex sentence: In 1923, he moved to Philosophy, Politics and Economics, the "new school" just being started at Oxford, graduating with second-class honors and, so he states, "no adequate qualification in any of the subjects" that he had studied.
Split into simpler sentences: In 1923, he moved to Philosophy, Politics and Economics, the "new school" that was just being started at Oxford. He graduated with second-class honors and, as he stated, "no adequate qualification in any of the subjects" that he had studied.