The classical scholar John Chadwick, who has died aged 78, played a leading role in one of the most important and exciting linguistic discoveries of the century, the decipherment of Linear B, the writing used by the Mycenaean civilisation of bronze-age Greece.

Incorrigibly modest, Chadwick always took second place to Michael Ventris, his colleague in the extraordinary breakthrough. Ventris had the original inspiration that the symbols of Linear B must represent syllables in an early version of Greek rather than some other, indeterminate eastern Mediterranean language. But, as one of his Cambridge colleagues confirmed after his death, Chadwick brought the expertise of a Greek philologist to the arduous and brilliant research, unaided by computers, that proved the theory.

Ventris was an architect but also an amateur linguist of genius. He had been interested in the mysterious, fire-hardened clay tablets, covered in pictograms and found in Crete and later in mainland Greece, ever since, as a schoolboy, he heard a 1936 lecture by their discoverer, the archaeologist Sir Arthur Evans. Evans identified two systems, Linear A, used by the earlier Minoan civilisation (definitely not Greek) and Linear B, which he never dreamed could be Greek.

Examining the Cretan tablets in 1951, Ventris deduced that certain groups of ideographic sylllables represented place-names on the island, which were often proto-Greek, such as ko-no-so for Knossos. In an experiment he ascribed the same sound-values to the same symbols when they appeared in other words whose meaning could be guessed from their design and context, such as pictograms for men, women, and children. Time after time the result seemed to resemble words in very ancient Greek.

Ventris therefore turned to Chadwick, then a Cambridge classics lecturer and a specialist in the early history of the language, for help. They published a controversial first paper in the Journal of Hellenic Studies in 1953 but were vindicated shortly afterwards when a new find of tablets at Pylos in Greece was deciphered using their method. The tablets contain lists of assets such as food, arms, livestock and people.

Not only had they "cracked" Linear B; by doing so they had shown for the first time that the Mycenaean civilisation that used it, more than 1,000 years before Pericles governed Athens, was Greek. It had ruled in Crete as well as such mainland sites as Mycenae, Tiryns and Pylos, for some 400 years until it was mysteriously destroyed, perhaps by a vast earthquake or volcanic explosion. The stunning discovery also lent strength to Homeric scholars who were confirmed in their theories about the date of the war against Troy and its destruction by bronze-age Greeks, as described by the poet centuries later.

Chadwick and Ventris wrote up their findings in the magisterial work, _Documents in Mycenaean Greek_, published in 1956 just before Ventris died in a car crash, and revised by Chadwick in 1973. He was the sole author of _The Decipherment of Linear B_ in 1958, which made an intricate process of decryption readably accessible to the lay reader.

John Chadwick was born at East Sheen, London, and educated at St Paul's School and Corpus Christi, Cambridge. After wartime Royal Navy Special Branch service he took his degree and started work as a lexicographer with Oxford University Press. Six years later he returned to Cambridge to lecture in classics, working in the university from 1952 until his 1984 "retirement" by which time he was Perceval Maitland Laurence Reader in classics.

But he carried on living in Cambridge, lecturing, writing and working on dictionaries until the day of his death. Reserved, he struck many people as aloof, even forbidding, an impression dispelled by closer acquaintance, according to other academics. he was particulary solicitous of his students, whith whom he kept in touch long after they went down.

Although never given a professor's chair, Chadwick was showered with academic honours by half a dozen countries and was a member of many leading international academic societies. He was also a Fellow of the British Academy and of Downing College, Cambridge. He wrote several further books on Mycenaean culture and other classical subjects and at the time of his death he had completed preparaions for a new Greek lexicon, which is to go ahead.

John Chadwick married Joan Isoblel Hill in 1947; they had one son.

In 1952 the decipherment of the Linear B script suddenly revealed the Greekness of Mycenaean Greece. Now, after new discoveries and more than 20 years of intensive work, scholars are able to interpret the written documents and reconstruct from them a vivid picture of life in this remote period, in a way which is impossible from archaeology alone. John Chadwick, who assisted Ventris in the original decipherment, has played a major part in these advances. He now summarizes the results of research and in so doing opens the door to a new world, Mycenaean Greece seen through the eyes of its inhabitants. The tablets may be only, as he describes them, 'the account books of anonymous clerks', but from these prosaic documents he shows how we can infer a bronze industry, foreign slave-women, or even human sacrifice. Not least important is the comparison of the newly available data with the Homeric account, much to the detriment of Homer's credibility as a witness.