Warner spent much of his academic career at St Peter's College, Oxford, where he was Lord White Fellow, and Tutor in English Literature from 1965 to 1999.[11] After retirement, he was elected Honorary Fellow of St Catharine's College, Cambridge, and emeritus Fellow of St Peter's College, Oxford.[12]
Warner produced several volumes of lyrical poetry early in his career and was honoured for his poetry as the recipient of the Messing Award (now known as the St. Louis Literary Award) in 1972 by the St. Louis University Library Associates. Warner began writing plays in the early 1970s, creating a body of theatrical work that would later be styled as the dramatic play cycle Agora. In addition to the plays in Agora, Warner continued writing poetry, publishing several volumes throughout his later literary years.
The dramatic cycle Agora encompasses the entirety of Warner's literary output as a dramatist. Consisting of 16 individual plays, loosely following a chronological order of action, Agora tracks the development of Western culture from ancient Greece to the present.
Agora: A Dramatic Epic
| Title | Publication year | Grouping |
| Healing Nature – The Athens of Pericles | 1988 | none |
| Virgil and Caesar | 1993 | Roman Trilogy |
| Moving Reflections | 1983 | Roman Trilogy |
| Light Shadows | 1980 | Roman Trilogy |
| Byzantium | 1990 | none |
| Living Creation – Medici Florence | 1985 | Europa Tetralogy |
| King Francis I | 1995 | Europa Tetralogy |
| Goethe's Weimar | 1997 | Europa Tetralogy |
| Rembrandt's Mirror | 2000 | Europa Tetralogy |
| A Conception of Love | 1978 | none |
| Emblems | 1972 | Maquettes for the Requiem |
| Troat | 1972 | Maquettes for the Requiem |
| Lumen | 1972 | Maquettes for the Requiem |
| Lying Figures | 1972 | Requiem Trilogy |
| Killing Time | 1976 | Requiem Trilogy |
| Meeting Ends | 1974 | Requiem Trilogy |