Question: What specialism did Alec Naylor Dakin, fellow of Oxford College, pursue at Bletchley Park during the second World War; a central site for British codebreakers?
Sentence (from "Bletchley Park"): According to the official historian of British Intelligence, the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and that without it the outcome of the war would have been uncertain.
Relevant evidence: No