Complex sentence: At St. Cyprian's, Blair first met Cyril Connolly, who became a noted writer and, as the editor of "Horizon", published many of Orwell's essays.
Split into simpler sentences: At St. Cyprian's, Blair first met Cyril Connolly, who became a writer. Many years later, as the editor of "Horizon", Connolly published several of Orwell's essays.