Byzantium, for Mark Whittow, had no boundaries. The sure- footed gusto with which he ranged across continents and centuries made him a Global Medievalist long before that now fashionable label was invented. A discussion might begin on the safely Byzantinist ground of the sixth-century Nile Valley and its Christian schisms, but within five minutes Mark would have you deep in the demography of early Tang China. Then mid-way through a careful recapitulation of statistics on population growth (and the numbers always wore a human face: what mattered to him here would be the implications for the prospects of textile workers) there would be a yelp and a cry of ‘And have you read…?’, and suddenly you would be among the Christian missions to the nineteenth-century Ibo, exploring the agencies – who was prodding whom, and with what, and how – at work there. This was not a dilettante's erudite rambling. You could be sure that you would end up back in the Nile Valley, but now the place would look excitingly different. To sit down with Mark was always to brace yourself for a journey, exhilaratingly bone- shaking; and there would be laughter, too, ‘shrieks and giggles’, all along the way. Sharing the world of Late Antiquity with him meant, and will continue to mean for all who knew him, having him always eagerly at your shoulder as you read and as you wrote, stabbing a footnote with a huntsman's excited cry, or else simply urging you on to the next page.

Mark's qualities as a historian were already apparent in his first major publication, a precocious paper in Past & Present in 1990. Not for him anything as mundane as the rehashing of his doctoral thesis. Instead, ‘Ruling the Late Roman and Early Byzantine City: A Continuous History’, was a careful and breathtakingly assured shepherding together of two constituencies which had had little to do with each other, the institutionally minded classical historians who plotted decline and fall through law-codes and literary texts, and the Byzantine archaeologists who were increasingly finding material that did not seem to suggest decline at all (if the two groups talk to each other more today than they did in 1990, this has much to do, in this city at least, with Mark's tireless commitment to interdisciplinary dialogue); and Mark took evident pleasure in re-reading the texts in such a way as to support an upbeat conclusion, finding in eighth- century Thessalonica, for example, ‘a lively, thriving community’. There was also a relish in the specifics, as he surveyed the society of sixth-century Emesa to discover ‘a world of innkeepers, grog shops, fast-food sellers (lupins!), glass-blowers and amulet-makers’; that most unacademic exclamation betrays the glee. And above all, there was already an insistence on the need to think comparatively – nearly thirty years on, it remains somehow thrilling that a paper on the late antique city should end in medieval Coventry.

The same features are still apparent in two recent papers, both from 2013. ‘Rethinking the Jafnids: New Approaches to Rome's Arab Clients’ again brings together two formidably erudite, and notoriously esoteric, disciplinary groups, the Byzantinists and the early Islamicists (noting wryly the ‘dialogue of the nearly deaf’ among the latter), again rejects defeatism in pointing instead to ‘a golden age of intensive agricultural exploitation’ and again reaches out towards new horizons, new points of comparison – in this case the Ottoman Near East, the ‘Five Civilized Tribes’ of early nineteenth-century America and, the trump card played in the conclusion, the Moors of Roman North Africa. In the second paper he asked, ‘How Much Trade was Local, Regional and Inter-Regional? A Comparative Perspective on the Late Antique Economy’, and his answer involved a sustained debate with Geoffrey Parker and his seventeenth-century crisis, and again focused on the speed and robustness of recovery rather than the catalogue of disasters. Here mediaeval England provides the key comparative case study, and provides a framework from which he swoops down, in his conclusion, to re-examine a fifth-century Tuscan peasant farmstead and to find green shoots among the potsherds. Mark's heroes, more and more explicitly in his later works, were hardworking ordinary people, and he had a rare gift for bringing to life the rewards that hard work could yield even in the most adverse circumstances. In these papers, too, we glimpse the lineaments of the book that he would never see to the press, on the transformations in the agricultural economy that constituted the ‘feudal revolution’. But even without the book, enough is already on record (for Mark's careless generosity bequeathed a remarkable number of papers to obscure conference volumes) for the outlines of his case to be clear.

One vital quality in all his published work is its sheer lucidity. These are specialist papers in a field not known for its accessibility, which nevertheless make a point of inviting in outsiders, setting out for them the currents of ongoing controversies, showing what is at stake for the opposing parties and encouraging the amateurs to make up their own minds. No wonder that his name features so prominently in undergraduate reading lists. And there is, above all, the book, The Making of Orthodox Byzantium, 600–1025 (1996), still fresh now two decades on, and the catalyst acknowledged by many of the current generation of Byzantine historians as the key to their conversion. This is a meticulous and reliable textbook which contrives simultaneously to be a mischievously unorthodox invitation to subversion. The Christian sectarian divisions that are so central to most previous accounts of the period are brushed aside, with Christianity becoming just another ingredient to a complex cultural compound, ‘a useful morale booster’ (p. 47); Latin pretensions are similarly dealt with in a lovely downplaying of the coronation of Charlemagne (p. 304); Byzantine mythologizing is likewise punctured by the reality check to which Basil the Bulgar-Slayer is subjected (pp. 387–388). The key to the book is the emphasis on historical geography, and the Eurasian world comes alive in the snapshots informed by years of intrepid autopsy: witness, for example, the agricultural potential identified in the ‘hot-house climate of steamy heat on the Caspian coast’ (p. 30).

Mark took evident pleasure in steering the small but sometimes fractious Late Antique and Byzantine Studies committee past the reefs on which it would otherwise have foundered, and the graciousness and skill with which he presided over Byzantine and Medieval research seminars boosted even the lamest of speakers with a sympathetic and constructive recapitulation (which would often contain more fruitful seeds for discussion than the paper itself) and seized with instant precision and unstinting enthusiasm upon what was most significant. We can look back further, to those careful and fair-minded summings-up which feature so prominently in his published work. The signs were already there in the terse verdict delivered, in that very first article of 1990, upon Saint Theodore of Sykeon, the Holy Man idealized by that generation of Byzantinists: ‘not an effective chairman’. Mark's career, in a sense, was an exercise in teaching the saint how it should be done.