Robertson unsuccessfully applied to be made a
fellow of Trinity in 1936: he was required to submit written work in support of his application, and did so on the material from Ithaca, but his examiner mistakenly sent Robertson's file to the Oxford art historian
John Beazley, who was supporting Dale Trendall's competing application. Robertson instead took a post in September 1936 as Assistant Keeper in the Greek and Roman department of the
British Museum, cataloguing the pottery from the excavations at
Al-Mina in Syria led by
Leonard Woolley in 1936–1937. Three members of staff left the museum's employment as a result; Robertson was not involved, and so kept his job (leaving him as the only member of the department). He was, however, demoted in seniority. As a consequence of the departures,
Denys Haynes was recruited as an Assistant Keeper, and the art historian
Bernard Ashmole, the
Yates Professor of Classical Art and Archaeology at
University College London, was brought in on a part-time basis to run the Department of Greek and Roman Antiquities. Haynes and Robertson became lifelong friends, and Robertson later wrote of the "precious apprenticeship" he gained from working with Ashmole. He resigned in 1948 to succeed Ashmole as Yates Professor at UCL. During his tenure in London, he began to grow a beard, but was ordered to stop by his superiors: his obituarist
Brian Sparkes wrote that they were concerned that he was displaying "arty" inclinations considered unbecoming of a professor. He was a visiting fellow of the BSA for the 1957–1958 academic year. He published his first book,
Greek Painting, in 1959. It used the surviving Greek paintings on vases and other artistic works to reconstruct now-lost
frescoes described by ancient authors. Between 1959 and 1968, he was chair of the governing council of the BSA. In 1961, Robertson again succeeded Ashmole, this time as
Lincoln Professor of Classical Archaeology and Art at the
University of Oxford, in which role he served until his retirement in 1978. He edited the second volume of the BSA's excavations at Perachora in 1962, following the deaths of Payne (who had conducted the excavations) and of the editors initially appointed to publish the work. In 1968–1969, he was a visiting scholar at the
Institute for Advanced Study in Princeton, New Jersey; he also held a visiting appointment at the
J. Paul Getty Museum in Los Angeles in 1980. In 1992, he published
The Art of Vase-Painting in Classical Athens, continuing and concluding his scholarly interest in Athenian painting. From 1994, Robertson suffered from
Guillain–Barré syndrome and
myasthenia gravis. He died of
cardiovascular disease and
bronchopneumonia at home in Cambridge on 26 December 2004, and was buried in
Cambridge City Cemetery. == Influence on classical scholarship ==