On graduating he moved on to the University of Durham to obtain Diploma of Education and then back to the Queen Mary College on a postgraduate scholarship intending to do his PhD under Dr Claus Viktor Bock on the 17th-century German polymath and polyglot Father Athanasius Kircher. His first task was to come to grip with Kircher's vast body of writings on most branches of learning of his age, for example: mathematics, astronomy, music, oriental languages - including Egyptian hieroglyphics, which Kircher was certain he had deciphered, but of course hadn't. The second task he and Dr. Bock set was to edit the immense correspondence from and to Kircher. Fletcher succeeded by 1966 in producing an extremely erudite thesis of over 900 pages - somewhere around the size of many of Kircher's own publications.