C.S. Lewis became Cambridge’s first chairholder of Medieval and Renaissance English in 1954.
The University of Cambridge appointed Lewis to the newly established Chair of Medieval and Renaissance English in 1954. He held the post until his death in 1963. The appointment came after a long Oxford career, where he had been a fellow and tutor at Magdalen College and had taught English literature.
The Cambridge chair recognized Lewis as a major scholar of earlier English literature, not merely as the author of Narnia and Christian books. His academic work included studies of medieval and Renaissance writing, literary history, allegory, and the development of English prose and poetry.
The wording of the title matters. Lewis was not Cambridge’s first English professor in general; he was the inaugural holder of this particular chair. He also continued to live in Oxford rather than moving permanently to Cambridge, commuting for his academic duties. That distinction explains why biographies associate him with both universities.