Frank Walbank, Emeritus Rathbone Professor of Ancient History at Liverpool University, was one of the great ancient historians of the 20th century. For around half a century he defined and dominated the field of Hellenistic history. Above all he was the unchallenged expert on the Greek politician and historian Polybius, who composed his history of Rome around the middle of the second century BC. Walbank's magnum opus is the monumental three-volume Historical Commentary on Polybius – a project launched in 1944 and completed in 1979 – which is widely regarded as the finest commentary ever composed on a historical author from antiquity.

Walbank also published the monograph Polybius (1972), and many of his 350-odd papers concerned the historian. Some of these papers were collected in two volumes (of 1985 and 2002); the second of these has an introductory chapter, "Polybian Studies c1975-2000". Walbank, remarkably, not only remained abreast of Polybian scholarship but was still contributing to it virtually until his death at the age of 98: his last article, on Fortune (tyche) in Polybius, appeared in 2007.

The collection of 2002, as indicated by the title, Polybius, Rome and the Hellenistic World, points to his mastery of Hellenistic history in general. In this area, one thinks especially of the two prize essays published as Aratos of Sicyon (1933) and Philip V of Macedon (1940), the Fontana Hellenistic World (1981, widely translated), and the three volumes of the revised Cambridge Ancient History which he co-edited and wrote for.

Curiously, the book for which he is best known in other fields of history and other cultures is an essay on the later Roman Empire, published in 1946 as The Decline of the Roman Empire in the West and reissued in 1969 as The Awful Revolution (recalling Gibbon). Walbank later distanced himself from some of its conclusions and from the Marxist views that inspired it, but nevertheless justified its composition as "a tract for the times", and stood by his attempt therein to explore the relevance of ancient history to the contemporary world.

Frank William Walbank was born at Bingley in the West Riding of Yorkshire in 1909. He was proud of his origins, and in his later days enjoyed studying old maps of Bingley, recalling incidents from his boyhood. His father, the son of a cobbler, won a scholarship to the Yorkshire College (later Leeds University) and became a schoolteacher; Frank was a scholar at Bradford Grammar School and then at Peterhouse, Cambridge, which he entered in 1928.

He had chosen Classics under the impression that Classics was the only means of entry into higher education and a career in one of the professions or the higher civil service. One suspects that his Classics teacher, Ned Goddard, fuelled this misapprehension, aware that he had in his charge an unusually talented student; the same man assigned him some Polybius (an unlikely author for a schoolboy), and later gave him his own multi-volume Encyclopaedia of Classical Antiquity (in German).

At Peterhouse, Walbank encountered the grammar school/public school division and like most others stayed with his own kind. It was something of an ordeal when James Mason (Marlborough, Peterhouse and Hollywood) invited him to tea to meet a friend of his from Trinity, who like Frank, had won a Hellenic Travellers' Club Prize. In scholarship, Walbank was totally at ease. One prize led to another, a brilliant performance in Tripos earned him a year of research, which included a summer spent learning German in Jena, and after a short spell as a Latin master in Manchester in 1932-33, he embarked on an academic career at Liverpool University in 1934.

He spent the Second World War in Liverpool with the University Tower Watch (a branch of the National Fire Service), having been prevented, to his great disappointment, from serving in the Home Guard and in Bletchley because of his radical political past. After the war, his academic career in Liverpool continued: the Chair in Latin (1946-51) was followed by the Chair in Ancient History and Classical Archaeology (1951-77). As a lecturer, he could hold any audience – undoubtedly his wartime experience in teaching the troops stood him in good stead; his writing style is marked by clarity, economy and quiet elegance.

Walbank was elected a Fellow of the British Academy at the early age of 43, was Dean of the Faculty of Arts and Public Orator in his own university, and was active in advancing the cause of Classics and Ancient History in the UK as a whole, taking his turn in steering bodies such as the Roman Society and Classical Association, and, not least, in participating regularly at seminars and conferences, in particular during his long and active retirement at Cambridge. He positively enjoyed meeting other scholars and hearing their lectures.

Overseas, he was a popular lecturer and visitor, and forged strong friendships with sundry academics in particular in North America, Germany, Italy and Israel. He had a lifelong connection with Albania, which country he visited with his wife Mary for the first time in 1936. Honours multiplied: abroad, in the United States, he was Sather Lecturer at Berkeley, Mellon Professor at Pittsburgh, Kentucky Colonel, and Member of the American Academy of Arts and Sciences; at home, he received an Honorary DLitt from Exeter University, was awarded the British Academy Kenyon Medal and appointed CBE (1993).

Frank Walbank bore his distinction lightly. He was aware of his lofty position in the world of classical scholarship, but seemed pleasantly surprised by it, and certainly did not glory in it. Joined with this rare modesty was an extraordinary generosity of spirit, an openness towards and tolerance of, others. He was immensely helpful to younger scholars, and very pleased to read their work, correspond with them, and get to know them.

He did have strong opinions, on scholarship, on politics, and on religion, but by and large kept them to himself and did not dwell on them. He was splendid company, had a ready wit and a great fund of stories, which he told with panache. His optimistic and positive attitude to life carried him through the loss of his wife and the various trials of old age; for others it was infectious and uplifting, in particular for his family (with whom he was very close) and friends. This was a man of high achievement and humanity who was regarded by all who knew him with the greatest respect and affection.

......... Peter Garnsey

Frank William Walbank, ancient historian: born Bingley, West Yorkshire 10 December 1909; Hugo de Balsham Research Student, Peterhouse 1931-32, Honorary Fellow 1984; Senior Classics Master, North Manchester High School 1932-33; Assistant Lecturer in Latin, Liverpool University 1934-36, Lecturer 1936-46, Professor of Latin 1946-51, Rathbone Professor of Ancient History and Classical Archaeology 1951-77 (Emeritus), Public Orator 1956-60; Dean, Faculty of Arts 1974-77; FBA 1953; CBE 1993; married 1935 Mary Fox (died 1987; one son, two daughters); died Cambridge 23 October 2008.