  In 1954, Gilbert Ryle visited New Zealand. He brought Prior an invitation to visit Oxford and deliver the John Locke lectures. Prior arranged a twelve month leave of absence from Canterbury and arrived in Oxford at the beginning of 1956. Rather quickly a small group began to form around him: Ivo Thomas, John Lemmon, Peter Geach. (His meetings with Prior were Lemmon’s first introduction to modal logic.) Hughes summarized the news arriving back home: ‘this wild colonial boy just hit Oxford and started to gather around him the main people [interested in] logic, and he started to organise a lot of parties, almost, for the serious doing of logic’. Prior kitted out his tiny rented apartment with a toyshop blackboard and held open house. On Mondays during Hilary and Trinity terms he lectured on modal logic, his great passion, and on tense logic, his great invention. The lectures were published the following year, under the title Time and Modality.