SIXTA was the largest of several sections at Bletchley Park dedicated to Traffic Analysis. Traffic Analysis examined the volume, direction, broadcast patterns, call signs and other characteristics of enemy message traffic, rather than the message content. This information gave vital insight into how enemy forces were organised and administered, and where they were located. It added useful context to decrypted message content and allowed intelligence to be gleaned even from unbroken messages. Each Traffic Analysis section worked on specific message types. SIXTA was part of the Hut 6 German Army and Air Force Enigma codebreaking operation, specialising in analysis of this traffic.
1 / 10 — SIXTA staff in Block G at Bletchley Park. Most SIXTA personnel were British Army men and women, serving in the Army’s No. 6 Intelligence School. Not all were Army, however. The woman on the far left of the image is Miss Elisabeth Roscoe, a Foreign Office civilian.