From 1968 to 1970, he left Oxford University to serve as Bursar of Gonville and Caius College, University of Cambridge. During this time he completed two books., one of which—Italian Manpower, 225 BC-AD 14 (Oxford University Press, 1971)—was arguably the most innovative book about Roman history written in English since the Second World War. In 1970, he was elected Camden Professor of Ancient History and joined Brasenose College, University of Oxford, as a professorial fellow.
From 1968 to 1970, he left Oxford University for Gonville and Caius College, University of Cambridge. During this time, he completed two books, one of which—Italian Manpower, 225 BC-AD 14 (Oxford University Press, 1971)—was considered the most innovative English book on Roman history since World War II. In 1970, he was elected Camden Professor of Ancient History and joined Brasenose College, University of Oxford, as a professorial fellow.