With Erdős's recommendation to Harold Davenport and a long struggle for permission from the Hungarian authorities, Bollobás was able to spend an undergraduate year in Cambridge, England. However, the authorities denied his request to return to Cambridge for doctoral study. A similar scholarship offer from Paris was also quashed. He wrote his first doctorate in discrete geometry under the supervision of László Fejes Tóth and Paul Erdős in Budapest University, 1967, after which he spent a year in Moscow with Israïl Moiseevich Gelfand. After spending a year at Christ Church, Oxford, where Michael Atiyah held the Savilian Chair of Geometry, he vowed never to return to Hungary due to his disillusion with the 1956 Soviet intervention. He then went to Trinity College, Cambridge, where in 1972 he received a second PhD in functional analysis, studying Banach algebras under the supervision of Frank Adams. In 1970, he was awarded a fellowship to the college.