She was a professor of Late Antique and Byzantine studies[2] and the Constantine Leventis Senior Research Fellow at King's College London (now emerita).

[5] Herrin worked as an archaeologist with the British School at Athens and on the site of Kalenderhane Mosque in Istanbul as a Dumbarton Oaks fellow.

Bowersock said in a New York Review of Books (NYRB) article that The Formation of Christendom had since its publication in 1987 meant "many historians suddenly discovered that early medieval Christianity was far more complex than they had ever imagined".

Norman Stone commented in The Guardian: "Herrin is excellent on the Ravenna of Justinian, with the extraordinary mosaics that somehow survived the second world war (when Allied bombing could be ruthless) and she is very good on that odd Byzantine (and Russian) phenomenon, the woman in power".

Their brains need some re-calibrating if they are to understand the rather different pattern of development that took place in the 'Rome of the East'; and that is the task which Judith Herrin has now performed, deftly and with much learning lightly worn".