Nearly 10,000 people worked in the wider Bletchley Park organisation
At first GC&CS followed its pre-war recruitment policy, and looked for ‘Men and women of a professor type’ through contacts at Oxford and Cambridge universities. Many famous Codebreakers including Alan Turing, Gordon Welchman and Bill Tutte were found this way. Others such as Dilly Knox and Nigel de Grey had started their codebreaking careers in WW1. The organisation started in 1939 with only around 150 staff, but soon grew rapidly.
As the codebreaking process became more mechanised, and the volume of intercepts grew, many more staff were recruited from a wider range of sources. A significant proportion of these were recruited from the Women’s Services; the WRNS, the ATS and the WAAF. By 1945, 75% of the staff of Bletchley Park were women, and of these six out of ten were in uniform. The remainder were recruited through the Civil Service. As a consequence civilians and uniformed personnel worked alongside each other in most sections. A small group of American service personnel were also brought over and integrated into a number of the Sections. The was the first time many of the UK staff had met an American, but the visitors fitted in very well.