John Herivel - Recruitment To Bletchley

Recruitment To Bletchley

John Herivel was born in Belfast, and attended Methodist College Belfast from 1924 to 1936. In 1937 he was awarded a Kitchener Scholarship to study mathematics at Sidney Sussex College, Cambridge. Shortly thereafter, Herivel was recruited to Bletchley Park by his former supervisor Gordon Welchman, head of the newly formed Hut 6 section created to solve Army and Air Force Enigma. Herivel, then aged 21, arrived at Bletchley on 29 January 1940, and was briefed on Enigma by Alan Turing and Tony Kendrick.

At the time, Hut 6 were having only limited success with the Luftwaffe Enigma network known as "Red". Herivel was working alongside David Rees, another Cambridge mathematician recruited by Welchman, in nearby Elmers School, testing candidate solutions and working out plugboard settings. The process was slow, however, and Herivel was determined to find a method to improve their attack, and would spend his evenings trying to think up ways to do so. One evening in the middle of February 1940 he was considering the procedures followed by a German operator when using Enigma, and identified a potential mistake that could greatly aid the codebreakers.