Complex sentence: He studied at Dulwich College Preparatory School and Westminster School, where he was a Queen's Scholar, then attended the Universities of Oxford and Cambridge, where he achieved a First in modern history and received an M.Phil in the history and philosophy of science.
Split into simpler sentences: He studied at Dulwich College Preparatory School and Westminster School, where he was a Queen's Scholar. He then attended the Universities of Oxford and Cambridge, where he achieved a First in modern history and received an M.Phil in the history and philosophy of science.